RU2738527C1 - Heat pump system for heating and cooling of rooms - Google Patents

Abstract

FIELD: heat power engineering.

SUBSTANCE: invention relates to heat engineering, in particular to heating and cooling units of low-rise buildings using low-potential heat sources. In heat pump plant there is external and internal heat exchangers with air, electrically driven compressor, four-way valve, capillary-throttle and pipelines connecting said elements into single unit filled with working medium - freon. In its freon loop is integrated additional heat exchanger, connecting freon loop with heat-carrier circuit of soil probes without intermediate heat carriers, four solenoid valves, controlled by external thermostat, allowing to cut off the installation during operation of external or additional heat exchanger.

EFFECT: technical result is achieved in the form of operation of heating and cooling unit with high KPI, exceeding KPI of prototype and described above analogues, and shorter period of low-potential soil heat use, reduction and complete elimination of danger of depletion of this source, possibility of its regeneration in summer during cooling unit operation.

1 cl, 2 dwg

Description

The invention relates to heat power engineering, in particular to heating and cooling installations for low-rise buildings using low-grade heat sources - outside air, soil and groundwater of the adjacent land plot.

Known installation of heating and hot water supply containing a heat pump (Application: 99119648/06, 13.09.1999) and as a source of low-grade heat using wastewater from a receiving well of wastewater. The installation consists of a heat exchanger-condenser that transfers heat to the heating and hot water supply system, a compressor, a throttle valve and a heat exchanger-evaporator connected by pipes into a single system filled with freon. The heat exchanger-evaporator is connected to a low-grade heat extraction device - a circulation loop filled with a liquid heat carrier. This circulation circuit consists of pipes, a circulation pump and a heat exchanger with a vibrator located in a wastewater collection well. The disadvantage of such an installation is the obligatory presence of a receiving well with a sufficiently large consumption of high temperature wastewater, for example, bath and laundry plants. A low-rise individual residential building will not be able to provide the required amount of wastewater, besides, the wastewater consumption is variable over time. The decrease in KPI * is evident due to these reasons.

* - energy conversion factor (hereinafter KPI), the term is used in refrigeration and heat pump technology. KPI is the ratio of heat (cold) performance of the installation to its electrical power. Heat- (cold) performance in watts usually exceeds the cost of electrical power, also expressed in watts, and the efficiency cannot be higher than 100%, therefore the term “energy conversion factor” is used in refrigeration and heat pump technology

Also known is an installation based on a geothermal heat pump of the water-to-water type associated with a system of ground probes http://remkasam.ru/kak-ustroen-i-kak-rabotaet-teplovoj-nasos.html. The installation consists of a heat exchanger-condenser that transfers heat to the heating and hot water supply system, a compressor, a throttle valve and a heat exchanger-evaporator connected by pipes into a single system filled with freon. The heat exchanger-evaporator is connected to a low-grade heat extraction device - a system of ground

probes. Soil probes consist of plastic pipes filled with a liquid heat carrier, placed in pairs in vertical wells. At the bottom of the well, two pipes

are connected in a U-shape. Ground probes are combined into a single circuit by a pair of horizontal pipes laid below the depth of soil freezing and supplied to a heat exchanger-condenser. The circulation of the coolant in the soil probes is provided by a circulation pump. The disadvantages of such a system are the extraction of soil heat during the entire heating period, which in most of the territory of Russia is 8-9 months and the lack of the possibility of regenerating low-potential soil heat during the conditioning season, which is 1.5-2 months or less in the same territory, and also the inability to increase the efficiency * to use the heat of the outside air during the period when its temperature is higher than the temperature of the heat carrier in the ground probes.

An installation based on an air-to-air heat pump is also known http://rems-info.ru/teplovoi-nasos-vozduh-vozduh.html The installation contains an internal heat exchanger that operates in the summer as an evaporator, and during the heating season as a condenser and an external heat exchanger with a fan, operating as a condenser in summer and as an evaporator during the heating season. The unit also contains an electrically driven compressor. four-way valve, throttle valve and pipes connecting the named units into a single unit. The unit circuit is filled with a working fluid - freon. Changing the functions of the heat exchangers is provided by a four-way valve. The disadvantage of such a system is a significant decrease in heat output with a decrease in the outside air temperature and the need to have some additional energy source for this period (electric heating element, or another heat source that uses fuel).

The closest technical solution to the proposed invention is the installation described in the application 116659/06, 31.05.2005, called the air conditioner-heater. The unit contains an internal heat exchanger that operates as an evaporator in summer and as a condenser during the heating season and an external heat exchanger with a fan that operates as a condenser in summer and as an evaporator during the heating season. The installation also contains a compressor with an electric drive, a four-way valve, a butterfly valve and pipes connecting the named units into a single installation. The unit circuit is filled with a working fluid - freon. Changing the functions of the heat exchangers is provided by a four-way valve. In contrast to the claimed invention, an external heat exchanger with a fan is placed in a heat-insulated sealed casing with hatches that let outside air inside the casing at an outside air temperature above a certain predetermined temperature, for example, minus 8 ⁰ C, equipped with a means for extracting soil heat - thermosiphons - vertical pipes filled with freon and buried in the ground, the upper part of which is located inside the casing and is equipped with a heat exchanger with air, and the freon of thermosyphons and freon of the installation circuit does not mix. Air and soil are used as sources of low-grade heat, as well as in the proposed invention, but the transfer of soil heat from thermosyphons to an external heat exchanger occurs through an intermediate heat carrier - air, which results in relatively high consumption of electrical energy, which lowers the KPI of the device. Another disadvantage of such an installation in comparison with the proposed invention are:

1. Limited capacity of the installation, proceeding from the limited area of the installation site of thermosyphons - vertical pipes, the top of which should be in a casing with an outdoor unit of the air conditioner. The power of thermosyphons will not exceed the power of one ground probe with the same depth. Also, the factor limiting the power is the natural convection of freon inside the thermosyphon, while in the ground probe the liquid heat carrier circulates forcibly;

2. The operation of thermosyphons to extract heat from the ground for a longer period of the heating season and the lack of the possibility of heat recovery from the ground due to the fact that the heat flow in the thermosyphon is directed only from the bottom up or is absent;

The objective of the present invention is to reduce energy costs, that is, to increase the efficiency, for heating and cooling rooms by creating a heat pump installation that uses two low-grade heat sources using two different heat exchangers.

The first analogue uses wastewater heat, which, as already indicated in the description of the analogue, may not be available. The second analogue uses only the heat of the ground, depleting the source and not using the heat of the air when it is warmer than the ground. The third analogue uses only the heat of the outside air, which becomes too little in cold weather and it becomes necessary to have some additional source of thermal energy for this period. The prototype - the air conditioner-heater uses two sources of low-grade heat, but through one heat exchanger, due to which the transfer of soil heat from thermosyphons to the external heat exchanger occurs through an intermediate heat carrier - air, which results in relatively high consumption of electrical energy, which lowers the efficiency of the device.

In this heat pump installation according to this invention, as in all split-system air conditioners and other heat pumps operating for cooling and heating, there are external and internal heat exchangers, a compressor with an electric drive, a four-way valve, a capillary-throttle and pipelines connecting the named elements into a single installation filled with a working fluid - freon. The task is solved by the fact that an additional heat exchanger is integrated into its freon circuit, connecting the freon circuit with the coolant circuit of the ground probes without intermediate heat carriers. This is how the described installation differs from the prototype and analogues. Soil probes consist of plastic pipes filled with a liquid heat carrier, placed in pairs in vertical wells. At the bottom of the well, the two pipes are connected in a U-shape. Soil probes are combined into a single circuit by a pair of horizontal pipes laid below the depth of soil freezing and supplied to an additional heat exchanger. The circulation of the coolant in the ground probes and an additional heat exchanger is provided by a circulation pump. Also in the freon circuit, the unit has four solenoid valves operating in the “open - closed” mode and controlled by an external thermostat.

Thanks to the use of an additional heat exchanger and ground probes, the unit can extract low-potential heat from the ground, which at low outdoor temperatures allows the unit to operate stably with high efficiency. Due to the presence of four solenoid valves in the installation, installed in pairs on the freon connections to the external and additional heat exchangers, it is possible to disconnect either the external or additional heat exchanger from the installation, leaving the heat exchanger in operation with the installation that will allow reaching the maximum efficiency at a given outdoor temperature in the mode heating. The function of switching the heat exchangers by means of solenoid valves, depending on the outside temperature, is carried out by an external thermostat.

So, thanks to the totality of the essential features of the invention, a technical result is achieved in the form of:

- operation of the unit for heating and cooling with a high KPI exceeding the KPI of the prototype and the analogs described above

- a shorter period of using the low-potential heat of the soil, reducing and completely eliminating the danger of depletion of this source, the possibility of its regeneration in the summer when the unit is operating for cooling.

The invention is illustrated by drawings (figure 1, figure 2) - schematic diagrams of the installation, in which all structural elements of the invention are schematically shown and numbered and their relationships with each other are shown. Figure 1 - operation of the cooling unit, figure 2 - operation of the heating unit.

Figure 1, Figure 2

1 - indoor heat exchanger

2 - fan blowing inside the heat exchanger

3 - external heat exchanger

4 - fan blowing outside heat exchanger with outside air

5 - four-way valve for freon

6 - compressor for freon

7 - capillary - freon circuit choke

8 - additional heat exchanger that allows you to get heat from the ground

9 - system of soil probes

10 - circulation pump for the heat carrier of soil probes

11, 12, 13, 14 - solenoid valves for disconnecting heat exchangers 3 or 8 from the freon circuit.

15 - external thermostat for controlling solenoid valves, circulation pump and fan of the external heat exchanger

The bold lines show the freon pipelines and the pipes of the ground probes, the thin lines show the outlines of the building, the ground surface and the control cables from the external thermostat 15.

The figures figure 1 and figure 2 show a diagram of a heat pump installation. The heat pump unit consists of a heat exchanger 1 located inside the room with a fan 2 blowing over it, which serves as an evaporator in the summer season, cooling the room, and during the heating period as a condenser, heating the room; and an external heat exchanger 3, with a fan 4 blowing over it, which does not work in the summer, and during the heating period at outdoor air temperatures above about minus 10 ° C, it is an evaporator, which during this period takes heat from the outside air. The heat exchangers are connected by means of pipes into a common system with each other and with a four-way valve 5, a compressor 6 and a capillary - a throttle 7. All air conditioners of the split-system type, as well as a prototype, are composed of these components. For stable operation for heating, at outside air temperatures below about minus 10 ° C, the heat pump unit includes a heat exchanger 8, which allows you to receive heat from the ground by means of soil probes 9. The pipes of soil probes are connected to the space around the heat exchanger coil 8 and are filled with antifreeze to minus 10 ° C with a heat carrier, for example, a 30% solution of ethyl alcohol, which circulates using a circulation pump 10. The heat pump circuit combines heat exchangers 1, 3, 8, a four-way valve 5, a compressor 6, a capillary-throttle 7 and solenoid valves 11, 12, 13, 14 as shown in the figure. The contour is filled with a working fluid, such as R410A freon.

The switching of low-grade heat sources during the heating season takes place by means of solenoid valves 11, 12, 13, 14, controlled by an external thermostat 15.

The essential features that distinguish the described invention are: the presence of three heat exchangers in one heat pump installation at once, one of which is internal and maintains a comfortable temperature inside the room, and two of which each use one source of low-grade heat - outside air and soil; four solenoid valves controlled by an external thermostat. These features save the described invention from the disadvantages of the prototype and analogues. With the help of these features, a technical result is achieved in the form of providing economical heating throughout the entire heating period with a high KPI that exceeds the KPI of the prototype and analogues; the possibility of economical use of low-potential soil heat without the danger of its depletion and with the possibility of its regeneration; economical air conditioning in summer.

The installation works as follows: in the summer, the four-way valve 5 combines the outputs in such a way that the heat exchanger 1 becomes the evaporator, and the heat exchanger 8 - the condenser (figure 1). In this case, the solenoid valves 11, 12 are closed, and the solenoid valves 13, 14 are open, the circulation pump 10 operates. The unit operates as an air conditioner to cool the room. The use of heat exchanger 8 as a condenser allows the unit to operate in cooling mode with lower power consumption, since heat is thrown not into the outside air with temperatures up to + 30 ° С, but into the ground, the temperature of which is + 5 ° С. This makes it possible to partially recover the heat of the soil around the ground probes spent during the heating season.

In this case, a fan coil can be used to condition the room, into which you can supply a coolant directly from the ground probes and save electricity on the operation of the compressor, but this is deliberately not done in this installation to reduce the cost of the system.

During the heating period, the four-way valve 5 makes the heat exchanger 1 a condenser, and the heat exchanger 3 or 8 becomes the evaporator. (Figure 2) The external thermostat 15 controls the operation of solenoid valves 11, 12, 13, 14 and has a setpoint of minus 10 ° C.

When the outside air temperature during the heating period is above minus 10 ° C, the external thermostat 15 gives a signal to open solenoid valves 11, 12, close solenoid valves 13, 14 and turn on fan 4 blowing outside heat exchanger 3. Pump 10 is off. In this case, the evaporator is heat exchanger 3. The unit takes heat from the outside air and saves ground heat.

When the outside air temperature during the heating period is below minus 10 ° C, the external thermostat 15 gives a signal to close the solenoid valves 11,12 and open the valves 13, 14, turns on the circulation pump 10 and turns off the fan 4 blowing around the external heat exchanger 3. The heat exchanger 8 becomes the evaporator, the installation takes heat from the ground, the heating capacity becomes more stable, independent of changes in the outside air temperature.

With this algorithm of operation of heat exchangers 3 and 8 as evaporators, the resource of soil heat at the ground probes is maximally saved, since in many regions, for example, in the Leningrad region, the outside air temperature during the heating period is above minus 10 ° C for an average of 7.5 months of the nine months of the heating season.

The described installation is practically used in a country house with an area of 18 sq. m in the Leningrad region and worked entirely for two heating seasons. The unit used a Lessar “Split-system” air conditioner with a wall-mounted type of indoor unit, in the freon circuit of which an additional heat exchanger is integrated to transfer heat from the liquid ground probes to freon and four solenoid valves. The rated power of the compressor is 800 W, the operating power is 720-820 W, depending on the temperatures of the indoor and outdoor air, the fan of the indoor unit with a power of 10 W, the fan of the outdoor unit - 30 W, a circulation pump with a power of 30 W. Due to the fact that the outdoor fan does not work simultaneously with the circulation pump, the total operating electrical power of the unit varies from 760 to 860 W.

At the same time, the heat output of the installation during the heating period varies from 2400 to 3400 W, the energy conversion coefficient is 3.2-4. There is an obvious energy saving of more than three times in comparison with traditional direct heating or heating by means of an electric boiler.

The economic benefit in the operating costs of electricity for the operation of the described heat pump installation is calculated in comparison with heating on all types of fuel except for main natural gas (which is always cheaper) and amounts to: 40% (firewood), 120% (liquefied gas), and up to 300% (diesel fuel) at prices for 2016 in the districts of the Leningrad region, adjacent to St. Petersburg or large regional centers, large horticultural tracts (with high prices for firewood).

Claims (1)

Heat pump installation for heating and cooling premises, including an internal heat exchanger with a fan, connected by one pipeline with a four-way valve, the other with a choke capillary; an external heat exchanger with a fan, connected by one pipeline with a four-way valve, the other with a choke capillary; an electrically driven compressor connected by both pipelines with a four-way valve; four-way valve; capillary choke; pipelines connecting the named units into a single unit filled with a working fluid - freon, with the possibility of reversing its operation thanks to a four-way valve; characterized in that it includes a device for extracting soil heat - a soil probe in the form of plastic pipes filled with a liquid non-freezing heat carrier, placed in pairs in vertical wells with a U-shaped connection of a pair of pipes at the lower point of the well; an additional heat exchanger connected by one freon pipeline with a four-way valve, the other with a throttle capillary, connecting the ground probe directly with the freon circuit of the installation; a circulation pump that drives the heat carrier through a ground probe; four solenoid valves, controlled by an external thermostat, allowing to cut off the external or additional heat exchanger from the unit during operation.

Images