CA2135762A1 - Temperature stabilization apparatus - Google Patents
Temperature stabilization apparatusInfo
- Publication number
- CA2135762A1 CA2135762A1 CA 2135762 CA2135762A CA2135762A1 CA 2135762 A1 CA2135762 A1 CA 2135762A1 CA 2135762 CA2135762 CA 2135762 CA 2135762 A CA2135762 A CA 2135762A CA 2135762 A1 CA2135762 A1 CA 2135762A1
- Authority
- CA
- Canada
- Prior art keywords
- cabinet
- temperature
- heat exchanger
- air
- equipment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/20536—Modifications to facilitate cooling, ventilating, or heating for racks or cabinets of standardised dimensions, e.g. electronic racks for aircraft or telecommunication equipment
- H05K7/20627—Liquid coolant without phase change
- H05K7/20654—Liquid coolant without phase change within rooms for removing heat from cabinets
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Landscapes
- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Microelectronics & Electronic Packaging (AREA)
Abstract
An illustrative embodiment of the invention provides a temperature stabilization apparatus for a closed equipment cabinet (10) in order to maintain the equipment (11) in the cabinet within predetermined temperature limits. A subterranean ground loop (32) is coupled to a heat exchanger (17) in which a portion of the ground loop is buried within the earth (33) to a depth at which the earth's temperature remains within predetermined limits. The heat exchanger (17) transfers heat between recirculated air (30, 31, 34, 35) within the cabinet and the earth (33) to provide the needed temperature stability for equipment within the cabinet. Water, in which its physicial state does not change, is the preferred working fluid for the ground loop.
Description
W093/~3875 PCT/US93/038?1 ~ 2135762 vTEMPERATURE STABILIZATION APPARATUS
TECHNICAL FIELD
This invention relates to a heat exchange system for maintaining, within a specified range, the temperature of apparatus in a cabinet, and more particularly, to a system that use the ground for stabilizing the temperature of electriral and mechanical telephone eguipment that is mounted within a ca~inet and in which recirculated air transfers heat directly between the telephone equipment and a ground loop, and the like.
BACXGROUND ART
T~ere is a need to stabili2e the temperature of lS equipment, and particularly electrical and mechanical telephone and power equipment, within ~ acceptable temperature range in order to mail.;ain the equipment at proper performance levels. Operating equipment that is subjected to extrem~ temperatures ~ends frequently to fail, resulting in increased maintenance costs and excessive out-of-service time. Equipment of this nature does not no~mally require the comfort temperat~.re range t70 to 75~F) that is required by human beings, but more typically can successfully operate in temperature ranges of 35 to 110F.
Further in this same regard, high humidity conditions in excess of 70%, considered uncomfortable for humans, are normally not a problem for electrical and mechanical equipment of this character.
~ ~arious methods have been employed to provide controlled heating and cooling within the aforementioned equipment temperature range, but all of these techniques have serious problems.
For example, some systems have employed electric heating, ~orced air cooling, and r~frigerant based cooling syste~s. Although each of these methods provides either ,~ W093t2307~ ~ 1 3 ~ 7 6 2 PCT/US93/03821 heating or cooling, or both, each method is subject tG a number of inherent limi~ations.
Electric resistance heat, although able to provide sufficient auxiliary heat within the cabinet t~ prevent freezing, suffers from a number of drawbacks. Electric resistance heat is very inefficient and expensive because electricity is used directly for heat rather than as a source to move or to transfer that heat, such as through a heat pump~ This inef~iciency contributes to a posr load factor at the power plant, higher levels of pollution to the atmosphere and higher operating costs for the user.
Forced air systems, which use the air as the primary cooling medium also suffer from a number of pro~lems. In these systems, heating is still provided through ele~trical resistance heaters, with their attendant problems, as mentioned above. Additionally, forced air convective cooling by means of fans that blow outside air across the equipment introduces airborne contaminants into these systems which can adversely affect many types of equipment. Acidity of this contained matter can cause 2~ electrical breakdowns, and dust buildup can reduce effective heat transfer. Adding outside filters reduces these airborne containments but increases maintenance costs and can restrict airflow as filters clog and reduce cooling capacity. Frequent maintenance is also required at high 2~ cost to the user.
A se~ondary set of problems related to the forced air method include high ambient noise levels outside of the cabinet due to fan rotation arld this contributes to noise pollution as well as possibly violating local noise 3~ ordinances. These fans, moreover, aggravate high temperature conditions on very hot days by increasi~g the temperature of the air that is drawn into the cabinet through the heat added ~y the fan apparatus. These very high temperature conditions tend to accalerate component failure.
~ W093/23875 2 1 3 ~ 7 6 2 PCT/US93/0382~
Still another method involves the use of an indirect exchange cooling process in which one fan is interior to the space within a cabln~t and a second f an is coupled with an air~based heat exchanger outside the cabinet. This method uses closed air circulation within the cabinet, transferring heat to a tube assembly that has additional surfac~ area outside the cabinet. Outside of the cabinet, either through natural or forced convection, heat -dissipation occurs. This method solves the interior air contamination problem but does not proYide effective cooling during high internal loading coupled with high outside temperatures. This condition requires excessively large heat exchange surface areas and external fans which are expensive. operating costs for this system can also be excessively high. Exposure, moreover, of the heat exchanger to outdoor climatic conditions can reduce effective life.
Additionally, hi~h temperature air on ~ery hot days reduces the cooling effecti~eness. This natural temperature fluctuation can create a thermal shock condition for the equipment or under sustained high temperature this indirect cooling system becomes a ~arginally effective means for cooling the equipment. This can cause a rapid reduction in e~uipment life.
Conventional air conditioners can effectively cool equipment and do enable isolation of outdoor air from indoor air. Further in this regard, air conditioners fail to perform efficiently on peak cooling days that coincide with very high equipment heat output. During these peak demand periods, cooling efficiencies are very low, with resulting ,higher o~erating cost,s. Air conditionexs also create other related pro~lems. Outdoor air, as the primary cooling medium still can introduce containments into filters adding to maintenance costs. Noise pollution is greater than with simple fans because they are augmented with compressor noises. Additionally, a power failure can render the cooling system inoperative and for certain critical W093~23~75 2 1 3 ~ 7 6 2 PCT/US93/03821 -- 4 -- .
applications where e~ipment must run on battery backup such as telephony equipment, the results could be catastrophic.
Air source heat pumps as cooling systems certainly reduce the e~ectric heat inefficiencies but suffer from all the other drawbacks of a conventional refrigerant based cooling systems. Further, during a power failure, emergency battery to keep the electrical equipment operational could require a great deal of capacity as well as complicated power inverters that may generate a considerable amount o~
electrical noise to permit heating or co~ling to continue.
A ground source heat pump system which uses the earth as the primary medium overco~es some of the noise and filter maintenance issues, because the heat exchange does not require interaction with the outside air. H~wever, the power failur problem as cited in connection with air source heat pumps remains unresolved. A further serious drawback of a ground s~urce heat pump system is its requirement to dissipate compressor heat underground during the cooling cycle. Compressors generate a great deal of hea~, and this heat adds to the burden that the system (of which the compressor is a part) must dissipate. Con~equent-y, this added compressor heat c~ntributes to the ground's thermal state and can lead to thermal saturation unless very large (and costly) ground heat exchangers are used. A related problem in the heating mode is the requirement for antifreeze within the ground source heat exchanger loop system. This antifreeze is required to prevent fluid freezing caused by the low. refrigerant temperatures developed within a ground source heat pump during the heating mode. The antifreeze, moreover, can reduce heat transfer effectiveness both during the heating and cooling modes.
All three refrigerant based systems are normally of fixed capacity in their ability to cool. Unfortunately, equipment within a cabinet can represent various levels of thermal loading and therefore can vary considerably in the - W093t23875 PCTtU~93/03~21 ~ 213~762 - 5 - , cooling capacity that is required~ Fixed capacity systems typically handle peak conditions well but become very inefficient as loads are reduced. Cycling losses due to frequent starts and stops contribute to the inefficiencies and add to the operating c~sts. Additionally, cooling equipment life is shortened.
All three refrigerant based systems, moreover, operate in the cooling mode with air coils below the dewpoint of air. This creates a dehumidification condition in which the system'requires water removal. Large volumes of water require large dry wells (at a cos~) and pose the threat of water spillage on the equipment if the drainage system fails. This is particularly hazardous to electronic equipment which is prone to fail through electrical shorting if water covers the connections.
All three refrigerant based systems also require a reasonable physical space either within the cabinet or outside in order to function. This physical space outside the cabinet is normally aesthetically unpleasant and in some cases is too close to property boundaries, therefore requiring awkward placement of the cabinet. Interior space is normally at a premium within the cabinet, thus large compressor based heating and cooling systems placed within the cabinet waste cabinet space.
- All three refrigerant based systems further 2~ require several large rotating motors to turn co~pressors and fans. These motors normally produce some level of electro-magnetic energy which can, when in close proximity to certain electronic components cause malfunctions due to duced !electri~cal noise. ' This interference is normally proportional to both the size of the field producing equipment and proximity to the operating electronics.
Special shialding can be introduced ~ut it adds to the cost and co~.p'icates air flow design.
Further, :hese three,refrigerant based cooling systems also requlre nonbenign ~ompounds that impose at - f~ W093f~3875 2 1 3 5 7 6 2 PCT/U~93/03821 , v least some environmental hazards in order to work.
Refrigerant leaks are possibla with each of these systems, particularly when equipment is vandalized or poorly maintained, and the negative impact on the environment in terms of ozone depletion could be significant if large numbers of these systems leaked refrigerant.
SUMMARY OF THE_INVENTION
To overcGme these, and other inadequacies of the prior art, an illustrative embodiment of the invention provides for direct heat exchange between recirculated air in a telephone equipment cabinet and the fluid in a fluid-to-ground heat exchanger. This ground loop allows heat in the circul~ting fluid to be dissipated or absorbed within the earth from the fluid circulated through the loop.
Alternatively, if the temperature of the telephone equipment is t~ be increased, the fluid will absorb heat from the ground and transfer that heat through a heat exchanger within the equipment cabinet directly to the recirculating air within the cabinet. A low power, direct current activated flow control assembly provides for this circulation and an air-to-fluid hea~ exchanger combined with a fan assembly, recirculates the air within the housing.
The fan assembly also can be of a variable speed in order to match the air flow to the thermal load imposed on the system. A control system regulates operation of the heat stabilization apparatus.
This invention takes advantage of the fact that ~, "
the average annual temperature at 10 to 25 feet below the earth's surface tends to be slightly highe.r than the average annual temperature for a particular region. Albany, New York, for instance has a typical temperature ra~ge of -20 to 100F. Neither of these extremes are coupled to the ground at depths below 15 feet. Thus, the earth as a heat exchange source or sink is stable at temperatures considera~ly below ~, , . .. , . . . ... , ~ .. ..
- ~ W093/23~5 ~ 1 3 5 7 6 2 PCT/US93~0~821 air temperature within the equipment cabinet.
In accordance with the invention, both heating and cooling operations are controlled by a thermostat that regulates the interior temperature of the cabinet. Unlike conventional temperature control required for human comfort, the control system for the present invention permits a broader range of acceptable temperatures ~or successful equipment opera~ion. This unique feature makes direct heat exchange both practical and cost effective, when compared with more complicated heat pump apparatus.
l0The use of the direct fluid-to-ground heat exchanger, coupled with the air-to-fluid heat exchanger eliminates refrigerant from the circuit, thereby avoiding - one of the major environmental concerns related to space condi~ioning~oday. Preferably, water, or if nec~ssary, lS water mixed with potassium acetate as an anti-freeze compound, is used as the circulating fluid because of its environmental acceptability and to insure that no temperature within the 1uid rircuit will go below the fluid's freezing temperature. Ordinary water, of course, does enhance the overall efficiency of heat exchange relative to other ~luids.
In accordance with another aspect of the invention the power requirements are very low in comparison- to compressor based systems. Additionally, circulators and 25 fans are readily avail~ble with direct current (DC) motors, :
whereas compressors are typically not DC driven. This ~;~
allows for simple, low wattage direct battery support for continued temperature stabilization during power failure to enable critical applications such as telephony equipment to continue operation within acceptable temperature .limits until normal power service is restored.
In accordance with a further aspect of the invention, the equipment can readily fit within the conditioned cabinet, virtually eliminating the outside noise pollution problem.
- ~ W093t~ ~ PCT/USg3/0~21 Recirculating the air within the cabinet, moreover, also eliminates the requirement for outdoor filters, again dramatically reducing the high maintenance costs of air based systems~ It is not possible to make ~abinets of this character completely air tight. Some migration into the cabinet of atmospheric air and entrained contaminants ordinarily can be expected, depending on ambient air conditions. For practical purposes, and for the purposes of this invention, air recirculation is adequately established if the external air flow into the cabinet is limited through the u~ual precautions, for in5tance, of neoprene gaskets on each cabinet door in order to isolate the air being recirculated within the cabinet from outside air. A typical cabinet that has a recirculating air system suitable for use with the invention is described in Northern Telecom Inc.'s "Product/Service Infor~ation" leaflet 5600.1 16/11-91, Issue 1, dated November 15, 1~91.
In accordance with yet another aspect of the invention, because there is no change in state for the fluid used in connection with the invention, the additional heat generated by the compressors in heat pumps that have been used in the past is eliminated, thereby reducing the thermal saturation that can occur with heat pumps that have been applied to ground loop systems. This adds to the overall improved performance of the ground loop design. Related to this, the normally unacceptable temperature swings developed with the ground source heat exchanger during heat transfer, though outside human comfort ranges, remain within the tolerances of most operating equipme~t.
In accordance with another aspect of the invention, the air to circulating fluid heat exchange will normally operate just above the dewpoint of air~ This will - greatly reduce the effects of condensation and Yirtually eliminate the problem of spillage from overflowing condensate pans, thereby eliminating the potential for an electrical failure that could develop as a consequence of - ~ W093/23~ 2 1 3 5 7 6 2 PCT/~S93/~
_ g _ condensate accumulation.
In accordance with another aspect of the invention, the low power circulators and fan do not generate the le~el of electromagnetic interference, or electrical signal noise, that could cause problems with respect to the housed equipment, in comparison with the much higher l~vels of electrical noise levels generated by compressors and large fan ~ssemblies that have characterized the prior art.
This virtually eliminates the requirement for electrical shielding.
The structure that exemplifies the invention is subject to a number of different embodiments. The invention, for example is best used in those applications that transfer thermal loads of 5 tons, or less, (one ton equals lZ,0~0 British thermal units per hour). Thus, the invention is admirably suited to electrical equipment thermal stabilization, because equipment of this nature typically creates thermal loads of 1/2 ton to 5 tons. The invention can be used to transfer greater thermal loads and for this purpose the novel apparatus that comprises the invention can be coupled with more conventional heat pump equipment in a hybrid, or combination design to accommodate larger equipment heat transfer requirements. Note, however, in these hybrid and combination systems, that the benefits of the invention do alleviate the undesirable features of these prior systems, at least to the extent that some of the thermal load is stabilized through apparatus that characterizes the invention. ;
Further, the invention also is adaptable to a plurality ofi pip'in`g fields, or ground loops ! buried in the earth. Each of these loops can be selectively connected to the fluid-to-air heat exchanger within the equipment cabinet. Switch ng ground loops in this manner reduces the potential for thermal saturation in the soil in the vicinity of each of these loops and a typical system for performing this function is described in Thomas F. O'Connell United ! W093~23~5 2 1 3 5 7 6 PCT/US93/03821 5tates Patent No. 4,360,056, granted November 23, 1982, for "Geokinetic Energy Conversion.~' These, and other features of the invention are apparent through the following detailed description o~ modes for carrying out the invention, when taken with the figures of the drawing.
BRIEF DESCRIPTION QF THE DRAWINGS
Fig. 1 is a perspective view of an e~uipment cabinet that illustrates features of the invention, with a por~ion of the top cover rem~ved in broken section;
Fig. 2 is a schematic diagram of a ground loop heat exchanger, ror use with the cabinet shown in Fig. 1;
and Fig. 3 is a perspective view of a typical air flow assembly for use with the cabinet shown in Fig. 1.
MODES FOR_CARRYING OUT_THE INVENTION
':
For a more complete appreciation of the invention, attention is in~ited to Fig. 1 which shows a generally re~ta~gular equipment cabinet 10 for housing electrical equipment 11, e.gO telephone apparatus. The cabinet 10 is essentially air tight, except for air vents 12 and 12' 2~ formed in top 14 of the cabinet 10.
In accordance with a salient characteristic of the invention, a generally rectangular housing lS is joined to the top 14 of the cabinet 10 to form a void space 16 between the top of the'housing 15 and the cabinet top `14 for air recirculation within the cabinet and housing combination, as described subsequently in more complete detail. Within the void space 16, an air-to-fluid heat ~xchanger 17 is secured to the housing 15. A flow control assembly 20 also is secured within the housing 15, between one end of the air-to fluid heat exchanger and a side wall of the housing.
- WOg3/23~ 2 1 3 S 7 PCT/US93/03821 A control box 21 also is nested within the housing 15 between one end of the flow control assembly 20 and a transversely disposed side of the housing 15. Although not shown in the drawing, the control box 21 contains a thermostat, or temperature sensing apparatus and suitable ele~ rical circuits to activate the flow c~ntrol assembly 20 in order to regulate the flow of fluid through the air-to-fluid heat exchanger 17 as described subsequently in more complete detail.
A fan assem~ly 22 also is secured to the housing 15 and positioned over the air vent 12' for the purpose of recirculating air through the interior of the equipment ~
cabinet 10 and the void space 16. ~-Attention now is invited to Fig. 3 which shows the structural q~tails of the fan assembly 22. As shown, a pair 1~ f fan impellers 23, ~4 each are driven respectively, by low power direct electrical current motors 25, 26. For some operations, Yariable speed fans might be preferrad, although a fan speed control cir~uit is not shown in the drawing.
Power for these motors is supplied either from a conventional rectified power supply (not shown in the drawing) or, in the case of a power failure, from battery 27 (Fig. 1) which is switched to the low power direct current motors 25, 26 through the operation of an appropriate emergency circuit in the control box 21. As illustrated in the Fig. 3 schematic, the fans 23, 24, when activated, draw air from the direction of the air-to-fluid heat exchanger 17, in the direction of arrows 30, 31, and discharge this recirculated air in the direction of arrows 28, 29 through the air vent 12' i(Fig. 1) in the cabinet top 14 in order to force this air through the second vent and into the interior of the equipment cabinet 10.
Fig. 2 shows an illustrative ground loop 32, which may be formed of polyethylene tubing. The ground loop 32 enables a working fluid, preferably water, to flow in a closed circuit, and without change of physical state, from _ WQ93/23875 2 1 3 ~ 7 6 2 P~T/US93/03821 a depth in earth 33 at which the earth's temperature remains within an acceptable temperature range. Ideally the tubing ~hat comprises the subterranean portion of the loop 32 is laid out within a drill borehole to optimize heat transfer with the earth ~nd to create turbulent flow in the tubing to improve overall heat transfer potential. The lower, or deeper part, of the subterranean portion of the loop 32 is encased in grouting mat rial 34 to establish a better thermal contact and to eliminate aquifer contamination. The upper portion of the loop 32 that is close ~o the earth's ~urface is enclosed in dirt, drill cuttings 35 and the like.
The ground loop heat exchanger is connectecl to the flow control assembly 20 through appropriate ground loop couplings 18 and 19. The water, moveover, follows a flow path from the loop 32 through the flow control assembly 20, lS air-to-fluid heat exchanger 17 and back to the ground loop.
In operation, as heat accumulates within the cabinet lO (Fig. l) through the operation of the electrical equipment ll, a sensor (not shown in Fig. l) responds to a temperature increase that exceeds a predetermined set point (e.g. 90F) by energizing the motors 25 and 26 which drive fan impellers 23, 24 (Fig. 3) within the fan assembly 27 (Fig~ l). When activated, the impellers draw recirculating air from the interior of the cabinet lO through the air vent 12 into the void space 16. The air from t~e vent 12 flows ?~ in the direction of arrows 34, 35 through the air side of the air-to-fluid heat exchanger 17. Within the heat exchanger ~7 the hot air from the cabinet lO transfer this heat to the cooler water on the wat~r side of the heat exchanger. This ¢ooled air then is drawn by th~ action of the fans in the direction of the arrows 30, 31 into t~e fan impellers 23, 24 (Fig. 3), respectively, in order to permit the fans to discharge this cooled air into the interior of the cabinet lO through the air vent 12~ for the purpose of cooling the electrical equipment within the cabinet.
At the same time that the circuit within the - W093/23~5 P~r/~Sg3~03821 ~135762 control box 21 activates the fan assembly, the circuit within the control box also activates the flow control assembly 20. When so activated, the flow control assembly 20 pumps water from the ground lnop 32 (Fig. 2) through the water side of the heat exchanger 17. In this manner, cool -~water from the ground loop 32 absorbs heat from the air that the fan assembly 22 (Fig. 1) drew through the heat exchanger 17. The warmer water then flows through the ground loop 3~
into the earth 33 where the heat is discharged to the cooler earth, thereby cooling the water. The cooled water then l~ completes its travel through the loop 32, the flow control assembly 20 and the heat exchanger 17.
In a similar manner, as the temperature of the air w~thin the equipment cabinet falls below some predetermined lower limit~(e.g~, 40F), a set point switch ~not shown) in the control box 21 once more energizes the fan assembly 22 to draw cold recirculating air o~ the heat exchanger 17. At the same time, the appropriate circuit (not shown) within the control box 21 causes the flow control assembly to pump relatively warmer water from the ground loop 32 (Fig. 2) in order to enable the water to heat the air within the heat exchanger 17. This warmed air then is pumped in the manner described above, back into the interior of the cabinet lO in order to keep the temperature of the electrical equipment 11 at or above the desired level for efficient operation.
During extended perisds of non-operation for the electrical e~uipment 11 in the cabinet 10, a condition may exist that could cause the fluid within the above-surface piping to freeze. The invention, consequently, also provides for the activation only of the flow control assembly 20 to maintain warmer fluid flow from the subterranean ground loop thrGIghout the system, thereby preventing freezing, burst piping and the like in these circumstances.
Should conventional sources of electrical power fail, a circuit within the control box 21 responds by - iW093J23~5 ~ 1 3 5 7 6 2 PCT/Us93~0382l - ~ switching not only its own operation but also that of the low power fan motors 2S, 26 (Fig. 3) and the flow control assembly 20 ~Fig. 1) to the battery 27.
It is important to note that in accordance with another feature of the invention the housing 15 and the temperature stabilizing equipment within the housing can be .-attached as a unit to existing equipment cabinets 10 in :
order to improve the thermal stability of these cabinets.
INDUSTRIAL APPLICABILITY ;
Thus, there is provided in accordance with the principles of the invention, a temperature stabilization -apparatus that largely overcomes the noise, contamination, eloctrical ~background signals, and environmental problems that have characterized the prior art. At the same time, the invention also pr~vides a more efficient and cost-effective temperature stabilization device than that which heretofore has been available.
Other aspects of the invention will be apparent to those of ordinary skill in the art.
r,~,i .... .
TECHNICAL FIELD
This invention relates to a heat exchange system for maintaining, within a specified range, the temperature of apparatus in a cabinet, and more particularly, to a system that use the ground for stabilizing the temperature of electriral and mechanical telephone eguipment that is mounted within a ca~inet and in which recirculated air transfers heat directly between the telephone equipment and a ground loop, and the like.
BACXGROUND ART
T~ere is a need to stabili2e the temperature of lS equipment, and particularly electrical and mechanical telephone and power equipment, within ~ acceptable temperature range in order to mail.;ain the equipment at proper performance levels. Operating equipment that is subjected to extrem~ temperatures ~ends frequently to fail, resulting in increased maintenance costs and excessive out-of-service time. Equipment of this nature does not no~mally require the comfort temperat~.re range t70 to 75~F) that is required by human beings, but more typically can successfully operate in temperature ranges of 35 to 110F.
Further in this same regard, high humidity conditions in excess of 70%, considered uncomfortable for humans, are normally not a problem for electrical and mechanical equipment of this character.
~ ~arious methods have been employed to provide controlled heating and cooling within the aforementioned equipment temperature range, but all of these techniques have serious problems.
For example, some systems have employed electric heating, ~orced air cooling, and r~frigerant based cooling syste~s. Although each of these methods provides either ,~ W093t2307~ ~ 1 3 ~ 7 6 2 PCT/US93/03821 heating or cooling, or both, each method is subject tG a number of inherent limi~ations.
Electric resistance heat, although able to provide sufficient auxiliary heat within the cabinet t~ prevent freezing, suffers from a number of drawbacks. Electric resistance heat is very inefficient and expensive because electricity is used directly for heat rather than as a source to move or to transfer that heat, such as through a heat pump~ This inef~iciency contributes to a posr load factor at the power plant, higher levels of pollution to the atmosphere and higher operating costs for the user.
Forced air systems, which use the air as the primary cooling medium also suffer from a number of pro~lems. In these systems, heating is still provided through ele~trical resistance heaters, with their attendant problems, as mentioned above. Additionally, forced air convective cooling by means of fans that blow outside air across the equipment introduces airborne contaminants into these systems which can adversely affect many types of equipment. Acidity of this contained matter can cause 2~ electrical breakdowns, and dust buildup can reduce effective heat transfer. Adding outside filters reduces these airborne containments but increases maintenance costs and can restrict airflow as filters clog and reduce cooling capacity. Frequent maintenance is also required at high 2~ cost to the user.
A se~ondary set of problems related to the forced air method include high ambient noise levels outside of the cabinet due to fan rotation arld this contributes to noise pollution as well as possibly violating local noise 3~ ordinances. These fans, moreover, aggravate high temperature conditions on very hot days by increasi~g the temperature of the air that is drawn into the cabinet through the heat added ~y the fan apparatus. These very high temperature conditions tend to accalerate component failure.
~ W093/23875 2 1 3 ~ 7 6 2 PCT/US93/0382~
Still another method involves the use of an indirect exchange cooling process in which one fan is interior to the space within a cabln~t and a second f an is coupled with an air~based heat exchanger outside the cabinet. This method uses closed air circulation within the cabinet, transferring heat to a tube assembly that has additional surfac~ area outside the cabinet. Outside of the cabinet, either through natural or forced convection, heat -dissipation occurs. This method solves the interior air contamination problem but does not proYide effective cooling during high internal loading coupled with high outside temperatures. This condition requires excessively large heat exchange surface areas and external fans which are expensive. operating costs for this system can also be excessively high. Exposure, moreover, of the heat exchanger to outdoor climatic conditions can reduce effective life.
Additionally, hi~h temperature air on ~ery hot days reduces the cooling effecti~eness. This natural temperature fluctuation can create a thermal shock condition for the equipment or under sustained high temperature this indirect cooling system becomes a ~arginally effective means for cooling the equipment. This can cause a rapid reduction in e~uipment life.
Conventional air conditioners can effectively cool equipment and do enable isolation of outdoor air from indoor air. Further in this regard, air conditioners fail to perform efficiently on peak cooling days that coincide with very high equipment heat output. During these peak demand periods, cooling efficiencies are very low, with resulting ,higher o~erating cost,s. Air conditionexs also create other related pro~lems. Outdoor air, as the primary cooling medium still can introduce containments into filters adding to maintenance costs. Noise pollution is greater than with simple fans because they are augmented with compressor noises. Additionally, a power failure can render the cooling system inoperative and for certain critical W093~23~75 2 1 3 ~ 7 6 2 PCT/US93/03821 -- 4 -- .
applications where e~ipment must run on battery backup such as telephony equipment, the results could be catastrophic.
Air source heat pumps as cooling systems certainly reduce the e~ectric heat inefficiencies but suffer from all the other drawbacks of a conventional refrigerant based cooling systems. Further, during a power failure, emergency battery to keep the electrical equipment operational could require a great deal of capacity as well as complicated power inverters that may generate a considerable amount o~
electrical noise to permit heating or co~ling to continue.
A ground source heat pump system which uses the earth as the primary medium overco~es some of the noise and filter maintenance issues, because the heat exchange does not require interaction with the outside air. H~wever, the power failur problem as cited in connection with air source heat pumps remains unresolved. A further serious drawback of a ground s~urce heat pump system is its requirement to dissipate compressor heat underground during the cooling cycle. Compressors generate a great deal of hea~, and this heat adds to the burden that the system (of which the compressor is a part) must dissipate. Con~equent-y, this added compressor heat c~ntributes to the ground's thermal state and can lead to thermal saturation unless very large (and costly) ground heat exchangers are used. A related problem in the heating mode is the requirement for antifreeze within the ground source heat exchanger loop system. This antifreeze is required to prevent fluid freezing caused by the low. refrigerant temperatures developed within a ground source heat pump during the heating mode. The antifreeze, moreover, can reduce heat transfer effectiveness both during the heating and cooling modes.
All three refrigerant based systems are normally of fixed capacity in their ability to cool. Unfortunately, equipment within a cabinet can represent various levels of thermal loading and therefore can vary considerably in the - W093t23875 PCTtU~93/03~21 ~ 213~762 - 5 - , cooling capacity that is required~ Fixed capacity systems typically handle peak conditions well but become very inefficient as loads are reduced. Cycling losses due to frequent starts and stops contribute to the inefficiencies and add to the operating c~sts. Additionally, cooling equipment life is shortened.
All three refrigerant based systems, moreover, operate in the cooling mode with air coils below the dewpoint of air. This creates a dehumidification condition in which the system'requires water removal. Large volumes of water require large dry wells (at a cos~) and pose the threat of water spillage on the equipment if the drainage system fails. This is particularly hazardous to electronic equipment which is prone to fail through electrical shorting if water covers the connections.
All three refrigerant based systems also require a reasonable physical space either within the cabinet or outside in order to function. This physical space outside the cabinet is normally aesthetically unpleasant and in some cases is too close to property boundaries, therefore requiring awkward placement of the cabinet. Interior space is normally at a premium within the cabinet, thus large compressor based heating and cooling systems placed within the cabinet waste cabinet space.
- All three refrigerant based systems further 2~ require several large rotating motors to turn co~pressors and fans. These motors normally produce some level of electro-magnetic energy which can, when in close proximity to certain electronic components cause malfunctions due to duced !electri~cal noise. ' This interference is normally proportional to both the size of the field producing equipment and proximity to the operating electronics.
Special shialding can be introduced ~ut it adds to the cost and co~.p'icates air flow design.
Further, :hese three,refrigerant based cooling systems also requlre nonbenign ~ompounds that impose at - f~ W093f~3875 2 1 3 5 7 6 2 PCT/U~93/03821 , v least some environmental hazards in order to work.
Refrigerant leaks are possibla with each of these systems, particularly when equipment is vandalized or poorly maintained, and the negative impact on the environment in terms of ozone depletion could be significant if large numbers of these systems leaked refrigerant.
SUMMARY OF THE_INVENTION
To overcGme these, and other inadequacies of the prior art, an illustrative embodiment of the invention provides for direct heat exchange between recirculated air in a telephone equipment cabinet and the fluid in a fluid-to-ground heat exchanger. This ground loop allows heat in the circul~ting fluid to be dissipated or absorbed within the earth from the fluid circulated through the loop.
Alternatively, if the temperature of the telephone equipment is t~ be increased, the fluid will absorb heat from the ground and transfer that heat through a heat exchanger within the equipment cabinet directly to the recirculating air within the cabinet. A low power, direct current activated flow control assembly provides for this circulation and an air-to-fluid hea~ exchanger combined with a fan assembly, recirculates the air within the housing.
The fan assembly also can be of a variable speed in order to match the air flow to the thermal load imposed on the system. A control system regulates operation of the heat stabilization apparatus.
This invention takes advantage of the fact that ~, "
the average annual temperature at 10 to 25 feet below the earth's surface tends to be slightly highe.r than the average annual temperature for a particular region. Albany, New York, for instance has a typical temperature ra~ge of -20 to 100F. Neither of these extremes are coupled to the ground at depths below 15 feet. Thus, the earth as a heat exchange source or sink is stable at temperatures considera~ly below ~, , . .. , . . . ... , ~ .. ..
- ~ W093/23~5 ~ 1 3 5 7 6 2 PCT/US93~0~821 air temperature within the equipment cabinet.
In accordance with the invention, both heating and cooling operations are controlled by a thermostat that regulates the interior temperature of the cabinet. Unlike conventional temperature control required for human comfort, the control system for the present invention permits a broader range of acceptable temperatures ~or successful equipment opera~ion. This unique feature makes direct heat exchange both practical and cost effective, when compared with more complicated heat pump apparatus.
l0The use of the direct fluid-to-ground heat exchanger, coupled with the air-to-fluid heat exchanger eliminates refrigerant from the circuit, thereby avoiding - one of the major environmental concerns related to space condi~ioning~oday. Preferably, water, or if nec~ssary, lS water mixed with potassium acetate as an anti-freeze compound, is used as the circulating fluid because of its environmental acceptability and to insure that no temperature within the 1uid rircuit will go below the fluid's freezing temperature. Ordinary water, of course, does enhance the overall efficiency of heat exchange relative to other ~luids.
In accordance with another aspect of the invention the power requirements are very low in comparison- to compressor based systems. Additionally, circulators and 25 fans are readily avail~ble with direct current (DC) motors, :
whereas compressors are typically not DC driven. This ~;~
allows for simple, low wattage direct battery support for continued temperature stabilization during power failure to enable critical applications such as telephony equipment to continue operation within acceptable temperature .limits until normal power service is restored.
In accordance with a further aspect of the invention, the equipment can readily fit within the conditioned cabinet, virtually eliminating the outside noise pollution problem.
- ~ W093t~ ~ PCT/USg3/0~21 Recirculating the air within the cabinet, moreover, also eliminates the requirement for outdoor filters, again dramatically reducing the high maintenance costs of air based systems~ It is not possible to make ~abinets of this character completely air tight. Some migration into the cabinet of atmospheric air and entrained contaminants ordinarily can be expected, depending on ambient air conditions. For practical purposes, and for the purposes of this invention, air recirculation is adequately established if the external air flow into the cabinet is limited through the u~ual precautions, for in5tance, of neoprene gaskets on each cabinet door in order to isolate the air being recirculated within the cabinet from outside air. A typical cabinet that has a recirculating air system suitable for use with the invention is described in Northern Telecom Inc.'s "Product/Service Infor~ation" leaflet 5600.1 16/11-91, Issue 1, dated November 15, 1~91.
In accordance with yet another aspect of the invention, because there is no change in state for the fluid used in connection with the invention, the additional heat generated by the compressors in heat pumps that have been used in the past is eliminated, thereby reducing the thermal saturation that can occur with heat pumps that have been applied to ground loop systems. This adds to the overall improved performance of the ground loop design. Related to this, the normally unacceptable temperature swings developed with the ground source heat exchanger during heat transfer, though outside human comfort ranges, remain within the tolerances of most operating equipme~t.
In accordance with another aspect of the invention, the air to circulating fluid heat exchange will normally operate just above the dewpoint of air~ This will - greatly reduce the effects of condensation and Yirtually eliminate the problem of spillage from overflowing condensate pans, thereby eliminating the potential for an electrical failure that could develop as a consequence of - ~ W093/23~ 2 1 3 5 7 6 2 PCT/~S93/~
_ g _ condensate accumulation.
In accordance with another aspect of the invention, the low power circulators and fan do not generate the le~el of electromagnetic interference, or electrical signal noise, that could cause problems with respect to the housed equipment, in comparison with the much higher l~vels of electrical noise levels generated by compressors and large fan ~ssemblies that have characterized the prior art.
This virtually eliminates the requirement for electrical shielding.
The structure that exemplifies the invention is subject to a number of different embodiments. The invention, for example is best used in those applications that transfer thermal loads of 5 tons, or less, (one ton equals lZ,0~0 British thermal units per hour). Thus, the invention is admirably suited to electrical equipment thermal stabilization, because equipment of this nature typically creates thermal loads of 1/2 ton to 5 tons. The invention can be used to transfer greater thermal loads and for this purpose the novel apparatus that comprises the invention can be coupled with more conventional heat pump equipment in a hybrid, or combination design to accommodate larger equipment heat transfer requirements. Note, however, in these hybrid and combination systems, that the benefits of the invention do alleviate the undesirable features of these prior systems, at least to the extent that some of the thermal load is stabilized through apparatus that characterizes the invention. ;
Further, the invention also is adaptable to a plurality ofi pip'in`g fields, or ground loops ! buried in the earth. Each of these loops can be selectively connected to the fluid-to-air heat exchanger within the equipment cabinet. Switch ng ground loops in this manner reduces the potential for thermal saturation in the soil in the vicinity of each of these loops and a typical system for performing this function is described in Thomas F. O'Connell United ! W093~23~5 2 1 3 5 7 6 PCT/US93/03821 5tates Patent No. 4,360,056, granted November 23, 1982, for "Geokinetic Energy Conversion.~' These, and other features of the invention are apparent through the following detailed description o~ modes for carrying out the invention, when taken with the figures of the drawing.
BRIEF DESCRIPTION QF THE DRAWINGS
Fig. 1 is a perspective view of an e~uipment cabinet that illustrates features of the invention, with a por~ion of the top cover rem~ved in broken section;
Fig. 2 is a schematic diagram of a ground loop heat exchanger, ror use with the cabinet shown in Fig. 1;
and Fig. 3 is a perspective view of a typical air flow assembly for use with the cabinet shown in Fig. 1.
MODES FOR_CARRYING OUT_THE INVENTION
':
For a more complete appreciation of the invention, attention is in~ited to Fig. 1 which shows a generally re~ta~gular equipment cabinet 10 for housing electrical equipment 11, e.gO telephone apparatus. The cabinet 10 is essentially air tight, except for air vents 12 and 12' 2~ formed in top 14 of the cabinet 10.
In accordance with a salient characteristic of the invention, a generally rectangular housing lS is joined to the top 14 of the cabinet 10 to form a void space 16 between the top of the'housing 15 and the cabinet top `14 for air recirculation within the cabinet and housing combination, as described subsequently in more complete detail. Within the void space 16, an air-to-fluid heat ~xchanger 17 is secured to the housing 15. A flow control assembly 20 also is secured within the housing 15, between one end of the air-to fluid heat exchanger and a side wall of the housing.
- WOg3/23~ 2 1 3 S 7 PCT/US93/03821 A control box 21 also is nested within the housing 15 between one end of the flow control assembly 20 and a transversely disposed side of the housing 15. Although not shown in the drawing, the control box 21 contains a thermostat, or temperature sensing apparatus and suitable ele~ rical circuits to activate the flow c~ntrol assembly 20 in order to regulate the flow of fluid through the air-to-fluid heat exchanger 17 as described subsequently in more complete detail.
A fan assem~ly 22 also is secured to the housing 15 and positioned over the air vent 12' for the purpose of recirculating air through the interior of the equipment ~
cabinet 10 and the void space 16. ~-Attention now is invited to Fig. 3 which shows the structural q~tails of the fan assembly 22. As shown, a pair 1~ f fan impellers 23, ~4 each are driven respectively, by low power direct electrical current motors 25, 26. For some operations, Yariable speed fans might be preferrad, although a fan speed control cir~uit is not shown in the drawing.
Power for these motors is supplied either from a conventional rectified power supply (not shown in the drawing) or, in the case of a power failure, from battery 27 (Fig. 1) which is switched to the low power direct current motors 25, 26 through the operation of an appropriate emergency circuit in the control box 21. As illustrated in the Fig. 3 schematic, the fans 23, 24, when activated, draw air from the direction of the air-to-fluid heat exchanger 17, in the direction of arrows 30, 31, and discharge this recirculated air in the direction of arrows 28, 29 through the air vent 12' i(Fig. 1) in the cabinet top 14 in order to force this air through the second vent and into the interior of the equipment cabinet 10.
Fig. 2 shows an illustrative ground loop 32, which may be formed of polyethylene tubing. The ground loop 32 enables a working fluid, preferably water, to flow in a closed circuit, and without change of physical state, from _ WQ93/23875 2 1 3 ~ 7 6 2 P~T/US93/03821 a depth in earth 33 at which the earth's temperature remains within an acceptable temperature range. Ideally the tubing ~hat comprises the subterranean portion of the loop 32 is laid out within a drill borehole to optimize heat transfer with the earth ~nd to create turbulent flow in the tubing to improve overall heat transfer potential. The lower, or deeper part, of the subterranean portion of the loop 32 is encased in grouting mat rial 34 to establish a better thermal contact and to eliminate aquifer contamination. The upper portion of the loop 32 that is close ~o the earth's ~urface is enclosed in dirt, drill cuttings 35 and the like.
The ground loop heat exchanger is connectecl to the flow control assembly 20 through appropriate ground loop couplings 18 and 19. The water, moveover, follows a flow path from the loop 32 through the flow control assembly 20, lS air-to-fluid heat exchanger 17 and back to the ground loop.
In operation, as heat accumulates within the cabinet lO (Fig. l) through the operation of the electrical equipment ll, a sensor (not shown in Fig. l) responds to a temperature increase that exceeds a predetermined set point (e.g. 90F) by energizing the motors 25 and 26 which drive fan impellers 23, 24 (Fig. 3) within the fan assembly 27 (Fig~ l). When activated, the impellers draw recirculating air from the interior of the cabinet lO through the air vent 12 into the void space 16. The air from t~e vent 12 flows ?~ in the direction of arrows 34, 35 through the air side of the air-to-fluid heat exchanger 17. Within the heat exchanger ~7 the hot air from the cabinet lO transfer this heat to the cooler water on the wat~r side of the heat exchanger. This ¢ooled air then is drawn by th~ action of the fans in the direction of the arrows 30, 31 into t~e fan impellers 23, 24 (Fig. 3), respectively, in order to permit the fans to discharge this cooled air into the interior of the cabinet lO through the air vent 12~ for the purpose of cooling the electrical equipment within the cabinet.
At the same time that the circuit within the - W093/23~5 P~r/~Sg3~03821 ~135762 control box 21 activates the fan assembly, the circuit within the control box also activates the flow control assembly 20. When so activated, the flow control assembly 20 pumps water from the ground lnop 32 (Fig. 2) through the water side of the heat exchanger 17. In this manner, cool -~water from the ground loop 32 absorbs heat from the air that the fan assembly 22 (Fig. 1) drew through the heat exchanger 17. The warmer water then flows through the ground loop 3~
into the earth 33 where the heat is discharged to the cooler earth, thereby cooling the water. The cooled water then l~ completes its travel through the loop 32, the flow control assembly 20 and the heat exchanger 17.
In a similar manner, as the temperature of the air w~thin the equipment cabinet falls below some predetermined lower limit~(e.g~, 40F), a set point switch ~not shown) in the control box 21 once more energizes the fan assembly 22 to draw cold recirculating air o~ the heat exchanger 17. At the same time, the appropriate circuit (not shown) within the control box 21 causes the flow control assembly to pump relatively warmer water from the ground loop 32 (Fig. 2) in order to enable the water to heat the air within the heat exchanger 17. This warmed air then is pumped in the manner described above, back into the interior of the cabinet lO in order to keep the temperature of the electrical equipment 11 at or above the desired level for efficient operation.
During extended perisds of non-operation for the electrical e~uipment 11 in the cabinet 10, a condition may exist that could cause the fluid within the above-surface piping to freeze. The invention, consequently, also provides for the activation only of the flow control assembly 20 to maintain warmer fluid flow from the subterranean ground loop thrGIghout the system, thereby preventing freezing, burst piping and the like in these circumstances.
Should conventional sources of electrical power fail, a circuit within the control box 21 responds by - iW093J23~5 ~ 1 3 5 7 6 2 PCT/Us93~0382l - ~ switching not only its own operation but also that of the low power fan motors 2S, 26 (Fig. 3) and the flow control assembly 20 ~Fig. 1) to the battery 27.
It is important to note that in accordance with another feature of the invention the housing 15 and the temperature stabilizing equipment within the housing can be .-attached as a unit to existing equipment cabinets 10 in :
order to improve the thermal stability of these cabinets.
INDUSTRIAL APPLICABILITY ;
Thus, there is provided in accordance with the principles of the invention, a temperature stabilization -apparatus that largely overcomes the noise, contamination, eloctrical ~background signals, and environmental problems that have characterized the prior art. At the same time, the invention also pr~vides a more efficient and cost-effective temperature stabilization device than that which heretofore has been available.
Other aspects of the invention will be apparent to those of ordinary skill in the art.
r,~,i .... .
Claims (12)
1 . A temperature stabilization apparatus for a closed equipment cabinet for maintaining equipment in the cabinet within predetermined temperature limits, comprising a housing, an air-to-fluid heat exchanger within the housing, a flow control within the housing and coupled to the heat exchanger for pumping fluid through the heat exchanger, a fan within the housing for recirculating air within the closed equipment cabinet through the heat exchanger, and a control circuit within the housing and responsive to the temperature in the cabinet for selectively activating said flow control and said fan as the temperature of the recirculated air that is recirculated within the closed equipment cabinet exceeds the predetermined limits.
2. A temperature stabilization apparatus according to Claim 1, further comprising a subterranean ground loop coupled to the heat exchanger in which a portion of the ground loop is buried within the earth to a depth at which the earth's temperature remains within the predetermined temperature limits.
3. A temperature stabilization apparatus according to Claim 2, further comprising a plurality of ground loops, each of said loops being selectively coupled to the heat exchanger to prevent thermal saturation of the earth in the vicinity of each of the ground loops.
4 . A temperature stabilization apparatus for maintaining equipment within predetermined temperature limits comprising a cabinet, said cabinet having a void space that communicates with the interior of said cabinet, an air-to-fluid heat exchanger within said void space, a flow control within said void space coupled to said heat exchanger for pumping fluid through said heat exchanger, a fan within said void space for recirculating air from within said cabinet through said heat exchanger, and a control circuit responsive to the temperature in said cabinet for selectively activating said flow control and said fan as the temperature of the recirculated air from within said cabinet exceeds predetermined temperature limits.
5. A temperature stabilization apparatus according to Claim 4, further comprising a subterranean group loop coupled to the heat exchanger in which a portion of the ground loop is buried within the earth to a depth at which the earth's temperature remains within the predetermined temperature limits.
6. A temperature stabilization apparatus according to Claim 5, further comprising a plurality of ground loops, each of said loops being selectively coupled to the heat exchanger to prevent thermal saturation of the earth in the vicinity of each of the ground loops.
7. A temperature stabilization apparatus according to Claim 4 and wherein said apparatus further comprises water within said air-to-fluid heat exchanger, said flow control.
8. A temperature stabilization apparatus according to Claim 7, further comprising telephone equipment within said cabinet for temperature stabilization by the apparatus.
9. A temperature stabilization apparatus according to Claim 7, further comprising electrical power distribution equipment within said cabinet for temperature stabilization by the apparatus.
10. A temperature stabilization apparatus according to Claim 4, wherein said control circuit further comprises circuit means for selectively activating said flow control and deactivating said fan to prevent said fluid from freezing.
11. A temperature stabilization apparatus for use in combination with another temperature stabilization system for maintaining equipment within predetermined temperature limits comprising a cabinet selectively closed to maintain the equipment within predetermined temperature limits, said cabinet having a void space that communicates with the interior of the cabinet, an air-to-fluid heat exchanger within said void space, a flow control within said void space coupled to the heat exchanger for pumping fluid through the heat exchanger, a fan within said void space for recirculating air from within said cabinet through the heat exchanger, and a control circuit responsive to the temperature of the recirculating air in the closed cabinet for selectively activating said flow control and said fan as the temperature of the recirculated air from within the cabinet exceeds either of the predetermined temperature limits in conjunction with the other temperature stabilization system.
12. A temperature stabilization apparatus according to Claim 11, further comprising a subterranean group loop coupled to the heat exchanger in which a portion of the group loop is buried within the earth to a depth at which the earth's temperature remains within the predetermined temperature limits.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US88375192A | 1992-05-15 | 1992-05-15 | |
| US883,751 | 1992-05-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2135762A1 true CA2135762A1 (en) | 1993-11-25 |
Family
ID=25383264
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2135762 Abandoned CA2135762A1 (en) | 1992-05-15 | 1993-04-23 | Temperature stabilization apparatus |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0640246A4 (en) |
| AU (1) | AU4112993A (en) |
| CA (1) | CA2135762A1 (en) |
| WO (1) | WO1993023875A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2774520B1 (en) * | 1998-02-02 | 2003-02-28 | Pouyet Sa | STREET ELECTRICAL CABINET |
| ES2172457B1 (en) * | 2000-12-22 | 2003-12-16 | Metalurgica Casbar S A | METHOD FOR HEAT DISSIPATION GENERATED IN ELECTRONIC EQUIPMENT CONTAINER CABINETS, IN UNDERGROUND TELECOMMUNICATION NETWORKS. |
| US20110247780A1 (en) * | 2010-04-12 | 2011-10-13 | Alcatel-Lucent Usa, Incorporated | Electronic system cooler |
| FI20120078L (en) * | 2012-03-15 | 2013-09-16 | Jukka Lempiaeinen | Geothermal base station |
| EP2677849A1 (en) * | 2012-06-20 | 2013-12-25 | C.I.S. Sud s.r.l. | Base transceiver station of a radio mobile telephone network, provided with a geothermal integrated conditioning system |
| ITRM20120288A1 (en) * | 2012-06-20 | 2013-12-21 | Cis Sud Srl | BASIC RADIO STATION OF A MOBILE RADIO TELEPHONE NETWORK EQUIPPED WITH GEOTHERMAL INTEGRATED AIR-CONDITIONING SYSTEM. |
| ITRM20120411A1 (en) * | 2012-08-13 | 2014-02-14 | Cis Sud Srl | BASIC RADIO STATION OF A MOBILE RADIO TELEPHONE NETWORK EQUIPPED WITH GEOTHERMAL INTEGRATED AIR-CONDITIONING SYSTEM. |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2181953A (en) * | 1936-03-24 | 1939-12-05 | Radie Corp Of America | Cooling system |
| US4624300A (en) * | 1985-04-24 | 1986-11-25 | Aire-Wrap, Inc. | Method and apparatus for heating and cooling buildings |
-
1993
- 1993-04-23 EP EP93910744A patent/EP0640246A4/en not_active Withdrawn
- 1993-04-23 CA CA 2135762 patent/CA2135762A1/en not_active Abandoned
- 1993-04-23 AU AU41129/93A patent/AU4112993A/en not_active Abandoned
- 1993-04-23 WO PCT/US1993/003821 patent/WO1993023875A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| WO1993023875A1 (en) | 1993-11-25 |
| EP0640246A4 (en) | 1996-01-17 |
| AU4112993A (en) | 1993-12-13 |
| EP0640246A1 (en) | 1995-03-01 |
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