RU2814739C1 - Heat pump - Google Patents

Abstract

FIELD: heat power engineering.

SUBSTANCE: invention relates to heat engineering, in particular, to thermal plants used for heating and cooling of premises. Heat pump comprises compressor, heat exchanger-condenser, liquid separator, circulation pump and controller arranged and fixed in the housing. Liquid separator is equipped with a window to control the level of liquid freon. On one side the compressor is interconnected with the inlet of the heat exchanger-condenser, and on the other side it is interconnected with the liquid separator made with possibility of communication on the other side with the outputs of the geothermal probes. First outlet of the heat exchanger-condenser is interconnected with the inlet of the circulation pump, which in its turn is made with the possibility of interconnection with the heat carrier circuit of the heating system. Heat exchanger-condenser contains the second output intended for communication with inputs of geothermal probes through uncontrolled expansion valves. Heat exchanger-condenser contains the second input intended for communication by means of the return pipeline with the heating system heat carrier circuit. Controller is connected to compressor and circulation pump. Controller is configured to change the speed of the circulating pump if, when the pressure at the compressor outlet changes, the permissible level of liquid freon in the liquid separator remains, and in case the level of freon rises during pressure change, the circulation pump is stopped.

EFFECT: providing stable performance of the heat pump, reducing the risk of emergencies, simplifying the design.

1 cl, 1 dwg

Description

The invention relates to thermal power engineering, in particular to thermal installations used for heating and cooling premises.

On the Russian market there are Danfoss geothermal heat pumps model DHP-S ECO (https://www.pea.ru/docs/equipment/heating/teplovye-nasosy/danfoss/dhp-s-eco/), containing a scroll compressor, three heat exchangers made of stainless steel (made using microchannel technology), built-in circulation pumps with frequency conversion, electronic throttling valve of the refrigeration circuit, weather-compensated controller, graphic display using R410A refrigerant.

The disadvantage of this technical solution is the complexity of its design and operation.

On the Russian market there are heat pumps of the Mitsubishi Electric brand of the ZUBADAN Inverter series (https://www.mitsubishi-aircon.ru/images/downloads/product_catalogue_2020/ME_ProductCatalogue2020_part08.pdf), in which liquid refrigerant exits the condenser (heat exchanger of the indoor unit ), and through the expansion valve (LEV B) enters the receiver, where heat is exchanged with the low-pressure gaseous refrigerant, due to which the temperature of the liquid refrigerant decreases, and it enters the outlet of the receiver. Next, a certain amount of liquid refrigerant is branched through another expansion valve (LEV C) into the injection circuit - the heat exchanger, where part of the liquid refrigerant evaporates and the temperature of the resulting vapor-liquid mixture decreases, due to this the main flow of liquid refrigerant passing through this heat exchanger is cooled. Next, the main flow of liquid refrigerant through the third expansion valve (LEV A) enters the evaporator (heat exchanger of the outdoor unit), where, due to the low evaporation temperature, heat is transferred from the outside air to the refrigerant, and it completely evaporates. As a result of passing through the low pressure pipe in the receiver, the superheat of the refrigerant gas increases and it enters the compressor. Part of the liquid refrigerant, branched from the main flow in the injection circuit, turns into a vapor-liquid mixture of medium pressure. In this case, the temperature of the mixture decreases, and it is supplied through a special injection fitting into the compressor, carrying out complete intermediate cooling of the refrigerant during the compression process. The expansion valve (LEV B) sets the amount of subcooling of the refrigerant in the condenser. The valve (LEV A) detects overheating in the evaporator, and (LEV C) maintains the temperature of the superheated steam at the compressor outlet at about 90°C. By adjusting the composition of the vapor-liquid mixture, you can control the compressor discharge temperature (the temperature at the compressor outlet).

The disadvantage of this technical solution is the complexity of its design and operation.

The heat pump "Mitsubishi Electric" ZUBADAN Inverter series (https://www.mitsubishi-aircon.ru/images/downloads/product_catalogue_2020/ME_ProductCatalogue2020_part08.pdf) was selected as a prototype.

The technical result achieved by the invention is to ensure stable performance of the heat pump, reduce the risk of emergency situations, and simplify the design.

The claimed technical result is achieved due to the fact that in a heat pump containing a compressor, a heat exchanger-condenser, a liquid separator, a circulation pump and a controller placed and fixed in the housing, the liquid separator is equipped with a window for monitoring the level of liquid freon, the compressor is connected on one side to the inlet heat exchanger-condenser, and on the other hand is connected with a liquid separator, configured to communicate on the other side with the outputs of geothermal probes, the first output of the heat exchanger-condenser
communicates with the input of the circulation pump, which, in turn, is configured to communicate with the coolant circuit of the heating system, the heat exchanger-condenser contains a second output intended for communication with the inputs of geothermal probes through unregulated expansion valves, in addition, the heat exchanger-condenser contains a second input intended for communication through the return pipeline with the coolant circuit of the heating system, the controller is connected to the compressor and the circulation pump, and the controller is configured to change the speed of the circulation pump, and in the event that the permissible level of liquid freon in the liquid separator is maintained when the pressure at the compressor outlet changes, If, when the pressure changes, the freon level also increases, stop the circulation pump.

The permissible level of liquid freon in the liquid separator can be no more than 10% of the height of the internal volume of the liquid separator.

The claimed invention is illustrated by the figure.

Positions on the figure:

1 - geothermal probes;

2 - compressor;

3 - heat exchanger-condenser;

4 - liquid separator;

4.1 – window in the liquid separator;

5 - circulation pump;

6 - unregulated expansion valves;

7 - controller;

8 – heating system.

The inventive heat pump contains a compressor 2, a heat exchanger-condenser 3, a liquid separator 4, a circulation pump 5 and a controller 7 located and fixed in a housing; the liquid separator 4 is equipped with a window 4.1 for monitoring the level of liquid freon; the compressor 2 on one side is connected to the input of the heat exchanger-condenser 3, and on the other side is connected to the liquid separator 4, which is configured to communicate on the other side with the outputs of geothermal probes 1; the first output of the heat exchanger-condenser 3 is connected to the input of the circulation pump 5, which, in turn, is configured to communicate with the coolant circuit of the heating system 8; heat exchanger-condenser 3 contains a second output intended for communication with the inputs of geothermal probes 1 through unregulated expansion valves 6; in addition, the heat exchanger-condenser 3 contains a second input intended for communication via a return pipeline with the coolant circuit of the heating system 8; controller 7 is connected to compressor 2 and circulation pump 5; wherein the controller 7 is configured to change the speed of the circulation pump 5, and if the pressure change also increases the freon level, stop the circulation pump 5 .

The permissible level of liquid freon in the liquid separator is no more than 10% of the height of the internal volume of the liquid separator and is determined by the amount of freon in the refrigeration circuit of the heat pump, and the condensation temperature (pressure) during stable operation of the heat pump.

At the input of liquid separator 4, freon comes from geothermal probes 1 in the form of a mixture of liquid and gaseous freon. During normal operation of the heat pump, the level of liquid freon in the liquid separator should be no more than 10% of the height of the internal volume of the liquid separator 4. In this case, only gaseous freon is supplied to the input of compressor 2. The pressure at the inlet and outlet of compressor 2 is measured, which for a specific heat pump operating under specific conditions must always be constant. With constant pressure at the inlet and outlet of compressor 2, constant performance of the heat pump as a whole is ensured, as well as stable operation of the circulation pump. This ensures adequate regulation of the speed of the circulation pump 5 depending on the required coolant temperature for the consumer.

When the temperature of the coolant decreases at a constant speed of the circulation pump 5, the condensation temperature (pressure) or pressure at the outlet of compressor 2 drops. When the pressure at the outlet of compressor 2 drops, its productivity increases, since the pressure at the inlet of compressor 2 is determined by the constant boiling point of freon in the geothermal circuit , the level of liquid freon in the liquid separator 4 increases. To prevent liquid freon from entering the inlet of compressor 2, controller 7, depending on the pressure at the outlet of compressor 2, reduces the speed of circulation pump 5, thereby increasing the condensation temperature or pressure at the outlet of compressor 2.

A change in pressure at the outlet of compressor 2 indicates that liquid freon has entered it, or indicates that such entry of liquid freon into the compressor is possible, which is unacceptable, because if the critical amount of liquid freon in the compressor 2 is exceeded, an emergency situation may occur due to a hydraulic shock in the compressor 2. In addition, if there is liquid freon in the compressor 2, the productive operation of the heat pump as a whole is disrupted, and the ability to adequately regulate the speed of the circulation pump 5 depending on on the required coolant temperature.

To prevent liquid freon from entering the compressor 2, the level of liquid freon in the liquid separator 4 is monitored (for example, visually) and the pressure at its outlet is controlled by means of a controller 7. As soon as the level of liquid freon in the liquid separator 4 exceeded the permissible level (more than 10% of the height of the internal volume of the liquid separator 4), the pressure at the outlet of the compressor 2 changed, and a command was sent from the controller output to the circulation pump 5 to change its speed in order to change the pressure at the outlet of compressor 2 to the required level. Water hammer in this case can be avoided due to the fact that the operation of the compressor 2 is regulated before the liquid freon enters the compressor 2. Such adjustment of the compressor operation is provided by the controller 7, which commands the circulation pump 5 to change the speed of its operation so that the pressure at the outlet of compressor 2 has returned to the required value.

If liquid freon does enter compressor 2 in some quantity, controller 7 instantly adjusts the speed of circulation pump 5 until a water hammer occurs. In this case, the heat pump can be stopped until liquid freon is removed from compressor 2.

The inventive heat pump operates as follows.

At the input of liquid separator 4 from geothermal probes 1, freon arrives in the form of a mixture of gaseous freon and not completely boiled off freon. Due to a sharp increase in volume (the volume of the liquid separator is greater than the volume of the geothermal probe pipes 1), the liquid freon boils to a boiling point in the liquid separator 4. In the best case, there should be no liquid freon left in the liquid separator 4 at all, but in any case, its amount should not exceed 10% of the height of the internal volume of the liquid separator 4.

From the output of liquid separator 4, gaseous freon enters the inlet of compressor 2. The pressure at the compressor inlet is measured; during normal operation of the heat pump, this pressure should always be constant. In compressor 2, gaseous freon is compressed and through the discharge pipeline enters the heat exchanger-condenser 3. During normal operation of the heat pump, the pressure at the outlet of compressor 2 should always be constant. The constant pressure at the inlet and outlet of the compressor 2 ensures constant performance of the heat pump, stable operation of the circulation pump 5, as well as adequate regulation of the coolant temperature for the consumer (heating system 8) through the circulation pump 5.

In the heat exchanger-condenser 3, heat exchange occurs between the gaseous freon and the coolant from the return pipeline of the heating system 8, in which the gaseous freon gives up its heat to the coolant of the heating system 8, as a result, condensation (cooling) of the gaseous freon occurs and it turns into a liquid state, and the heated coolant through the circulation pump 5 it moves from the heat exchanger-condenser 3 to the supply line of the heating system 8.

From the heat exchanger-condenser 3, liquid freon flows through the pipeline into the geothermal probes 1 through expansion valves 6 (for example, capillary tubes).

Liquid freon through unregulated expansion valves 6, expanding at their outlet, enters geothermal probes 1, which serve as an evaporator. The ends of the geothermal probes 1 are combined in a collector 9, which can be located inside the body of the heat pump, which makes it possible to reduce the occupied space when connecting the inventive heat pump with geothermal probes and connecting to the heating system 8. In the geothermal probes 1, liquid freon boils, resulting in the formation a vapor-liquid mixture (that is, liquid freon and gaseous freon formed during boiling), which is supplied through the collector 9 to the liquid separator 4 located in front of the entrance to the compressor 2, where the liquid freon boils to a boiling point and passes into a gaseous state, after which the gaseous freon enters the compressor inlet 2.

During the operation of the heat pump, visual monitoring of the level of liquid freon in the liquid separator 4 is carried out in order to assess the possibility of liquid freon entering the compressor 2), and also, through the controller 7, the pressure at the outlet of the compressor 2 is monitored and when the specified pressure changes (while maintaining the amount of liquid freon in the liquid separator 4 is at an acceptable level), a command is sent from the controller 7 to the circulation pump 5 to change the speed of the pump 5 in order to return the pressure at the outlet of the compressor 2 to the required level.

If at the same time there is an increase in the amount of liquid freon in the liquid separator 4 and a change in pressure at the outlet of the compressor 2, then this may indicate liquid freon entering the compressor 2. In this case, a command is received from the output of the controller 7 to stop the operation of the heat pump (stop the circulation pump 5), because the pressure at the outlet of compressor 2 in such a situation will change critically, to a greater value than in the absence of liquid freon in compressor 2. This prevents an emergency situation associated with possible water hammer and damage to compressor 2.

Thus, the pressure at the outlet of compressor 2 is controlled in order to prevent liquid freon from entering compressor 2 or to stop the operation of the heat pump if liquid freon does enter compressor 2.

As a rule, when liquid freon enters compressor 2 (or if a situation arises in which liquid freon can enter compressor 2), the pressure at the outlet of compressor 2 drops. By adjusting the speed of the circulation pump 5 (lowering its speed), the pressure at the outlet of the compressor 2 is increased.

However, there may be situations when the pressure at the compressor outlet increases (for example, during a water hammer or in the absence of liquid freon in compressor 2 only due to an increase in the pressure of gaseous freon), in this case, a command is received from the controller 7 to the circulation pump to increase the speed his works. As a result, the pressure at the outlet of compressor 2 will decrease to the required level.

In known analogues, maintaining the required operating mode of the compressor is ensured by adjustable valves, which either open or close depending on the temperature and pressure at the inlet to the compressor. At the same time, the operation of adjustable valves is also controlled by controllers.

In the claimed invention there is no need to use special adjustable valves. The ability to adjust the operating mode of compressor 2 in the inventive heat pump is provided directly by the circulation pump present in all heat pumps. The command to change the speed of its operation comes from the controller (also present in all heat pumps). Only in the claimed heat pump, the controller does not control the operation of adjustable valves, but controls the speed of the circulation pump depending on the controlled parameter - the pressure at the outlet of compressor 2.

Thus, as a result of the implementation of the claimed invention, the design and operation of the heat pump is simplified, and the reliability of the heat pump operation is also increased. The stable performance of the inventive pump also helps to increase its reliability and trouble-free operation. The specified reliability and stability are ensured by simple means. This ensures stable, trouble-free operation of the heat pump without the need to use additional adjustable valves.

Claims (2)

1. A heat pump containing a compressor, a heat exchanger-condenser, a liquid separator, a circulation pump and a controller located and fixed in the housing; the liquid separator is equipped with a window for monitoring the level of liquid freon; the compressor is connected on one side to the input of the heat exchanger-condenser, and on the other side communicated with a liquid separator configured to communicate on the other side with the outputs of geothermal probes, the first output of the heat exchanger-condenser communicates with the input of the circulation pump, which, in turn, is configured to communicate with the coolant circuit of the heating system, the heat exchanger-condenser contains a second output , designed for communication with the inputs of geothermal probes through unregulated expansion valves; in addition, the heat exchanger-condenser contains a second input intended for communication
through a return pipeline with the coolant circuit of the heating system, the controller is connected to the compressor and the circulation pump, wherein the controller is configured to change the speed of the circulation pump if the pressure at the compressor outlet changes and the permissible level of liquid freon in the liquid separator is maintained, and in the case If, when the pressure changes, the freon level also increases, stop the circulation pump. 2. The heat pump according to claim 1, characterized in that the permissible level of liquid freon in the liquid separator is no more than 10% of the height of the internal volume of the liquid separator.