JP2012233605A - Liquid circulation heating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid circulation heating system for forming liquid of a use side, at high temperature and stably.SOLUTION: The liquid circulation heating system includes: a compressor 3 for circulating a refrigerant in a heat source side and regulating a circulation flow rate; a circulation pump 6 for circulating liquid via a heat radiator 22 installed in a room and regulating the circulating flow rate; a heat exchanger 4 for exchanging heat between the refrigerant and the liquid; a forward liquid temperature setting means 23 for setting a preset temperature of temperature of the liquid to be fed to the heat radiator 22; a forward temperature detection means 7 for detecting a temperature of the liquid to be fed to the heat radiator 22; and a return liquid temperature detection means 8 for detecting a temperature of the liquid having returned through the heat radiator 22. The circulation pump 6 regulates a circulation flow rate of the liquid so that a difference of temperatures respectively detected by the forward liquid temperature detection means 7 and the return liquid temperature detection means 8 will fall within a desired range, and the compressor 3 regulates the circulation flow rate of the refrigerant so that the temperature detected by the forward liquid temperature detection means 7 will fall within a desired range including the preset temperature.

Description

  The present invention relates to temperature generation of a use-side liquid in a liquid circulation heating system that constitutes a heat pump cycle that exchanges heat between a heat-source-side refrigerant and a use-side liquid via a heat exchanger.

  Conventionally, there has been known a liquid circulation heating system that heats a use-side liquid by a boiler using kerosene as a heat source and transports the use-side liquid to a radiator such as a floor heating panel installed in a room for heating. In recent years, a liquid circulation heating system called a heat pump type hot water heating system that uses a heat pump as a heat source for heating a liquid has become widespread. The heat pump circulates a refrigerant represented by chlorofluorocarbon as a medium on the heat source side, collects heat from the outside air, etc., and performs heat exchange with the liquid on the usage side, and because a high output is obtained with respect to the input, As an efficient heat source, it is attracting attention as a heat source that replaces conventional boilers.

  Here, the liquid temperature on the usage side that can be heated by a boiler that burns conventional kerosene or the like can be up to about 70 ° C., but the liquid temperature on the usage side that is generated by a refrigerant such as R410A used as a heat pump hot water heating system. Is about 60 ° C. at the maximum. In particular, as a heat pump heating refrigerant for hot water supply, a technique for generating a high-temperature liquid of 70 ° C. or higher using carbon dioxide is disclosed.

JP 2003-106691 A

Mitsubishi Heat Pump Hot Water Heating System Catalog October 2010

  By the way, according to the above-mentioned conventional technology, when there is a case where the heat source is replaced with a heat pump type from a conventional boiler due to failure or maintenance cost reduction, the use side liquid temperature is conventionally used. If it cannot be generated at the same high temperature as the boiler, it will cause a problem that it will not be heated by the radiator on the use side.

  However, the refrigerant such as R410A, which is often used as a refrigerant in a heat pump type liquid circulation heating system, has a low critical temperature and cannot generate a high temperature exceeding 60 ° C. in the first place. In addition, the water temperature of the liquid on the use side is determined by the balance between the temperature of the liquid that has been radiated and returned in the room, the circulation flow rate, and the amount of heat that the refrigerant on the heat source side has, so a refrigerant with a higher critical temperature was used. However, it is not always possible to generate high-temperature water.

  In particular, if the circulation flow rate of the liquid on the user side is unnecessarily large, not only high-temperature water cannot be generated, but also the difference between the temperature going back to the radiator and the temperature returning from the radiator is not possible, and the heat source that exchanges heat Side efficiency will be reduced.

  In addition, in the system that circulates the liquid on the use side, the return water temperature is relatively high for a refrigerant such as carbon dioxide, which is efficient for using the region exceeding the critical temperature (supercritical) and raising the low temperature to a high temperature. For this reason, the performance (capacity and efficiency) is greatly reduced, and it is not suitable for use in a liquid circulation heating system.

  This invention is made | formed in view of the above, Comprising: It aims at obtaining the liquid circulation heating system which produces | generates the liquid of a utilization side stably at high temperature, without reducing the efficiency of a heat pump cycle.

  In order to solve the above-described problems and achieve the object, the present invention circulates by circulating a liquid through a compressor that circulates refrigerant on the heat source side and adjusts the circulation flow rate, and a radiator installed indoors. A circulation pump for adjusting the flow rate, a heat exchanger for exchanging heat between the refrigerant and the liquid, a forward liquid temperature setting means for setting a temperature of the liquid sent to the radiator, and a radiator A forward liquid temperature detection means for detecting the temperature of the liquid; and a return liquid temperature detection means for detecting the temperature of the liquid returned through the radiator, the forward liquid temperature detection means and the return liquid temperature. The circulating pump adjusts the circulation flow rate of the liquid so that the difference between the temperatures detected by the detecting means falls within a desired range, and the temperature detected by the forward liquid temperature detecting means includes a desired range including the set temperature. So as the compressor and adjusting the circulation flow rate of the refrigerant.

According to the present invention, a refrigerant having a high critical temperature is used, and the circulation flow rate is adjusted so that the difference in the return and return temperature of the liquid on the use side is within a certain range. As a result, it is possible to obtain a liquid circulation heating system capable of generating high temperatures without reducing the efficiency of the heat pump.
It becomes.

FIG. 1 is a diagram showing a configuration of a liquid circulation heating system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a simplified Mollier diagram of the refrigerant according to the embodiment of the present invention. FIG. 3 is a flowchart showing the control operation of the circulation pump of the liquid circulation heating system according to the embodiment of the present invention. FIG. 4 is a flowchart showing the control operation of the compressor of the liquid circulation heating system according to the embodiment of the present invention.

  Embodiments of a liquid circulation heating system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram showing a configuration of a liquid circulation heating system 100 according to an embodiment of the present invention. The liquid circulation heating system 100 includes a heat pump heat source device 21, an indoor radiator 22 connected to the heat pump heat source device 21 and a connection pipe 24.

  As shown in FIG. 1, the heat pump heat source unit 21 that generates a liquid heat medium used for heating with heat collected by the heat pump cycle collects heat from the outdoor air by blowing air from the heat source side blower fan 1 and the heat source side blower fan 1. Heat source side heat exchanger 2 that heats, compressor 3 that compresses the refrigerant that circulates in the heat pump cycle and conveys heat, refrigerant flow rate adjustment valve 10 that adjusts the flow rate of the refrigerant, and heat exchange between the refrigerant and the liquid heat medium The refrigerant on the heat source side is a closed circuit of the heat medium constituted by the primary flow path of the liquid heat exchanger 4, the circulation pump 6 as the water supply means for circulating the liquid heat medium, and the liquid heat medium as the refrigerant— A circuit on the use side for heating through the liquid heat exchanger 4 is provided.

  The refrigerant of the heat pump cycle and the liquid heat medium of the indoor radiator circulation cycle are independent from each other and are not thermally mixed but are thermally connected by the refrigerant-liquid heat exchanger 4.

  An indoor radiator 22 that performs heating operation with a liquid heat medium supplied from the heat pump heat source device 21 is connected to the circuit on the use side through a connection pipe 24.

  The liquid heat medium returned from the indoor radiator 22 is sent to the refrigerant-liquid heat exchanger 4 through the circulation pump 6, exchanges heat with the refrigerant on the heat source side, is heated, and is conveyed to the indoor radiator 22.

  The circulation pump 6 has an impeller. By rotating the impeller, the liquid heat medium in the circulation circuit is forcedly circulated, and the liquid heat medium is circulated through the indoor radiator 22. The embodiment of the present invention includes a motor that is PWM controlled by a control means 9 including a microcomputer that controls the circulation pump 6, the compressor 3, and the heat source side fan 1 that collects the heat of outdoor air, and the like. A pump that is driven by a DC power source that can arbitrarily change the rotation speed of the impeller by a command voltage is used as the circulation pump 6.

  In addition, one or a plurality of indoor radiators 22 that perform a heating operation by a liquid heat medium supplied from the heat pump heat source unit 21 and a controller 23 corresponding to the indoor radiators 22 are provided in the room. The indoor radiator 22 is installed under the floor. Although not shown in detail, a floor heating panel that performs radiant heating, a panel heater that is installed on the wall surface of the room and performs radiant heating, a blower for circulating indoor air, indoor air and a liquid heat medium, Includes a heat exchanger that performs heat exchange, a fan convector that performs heating by forced convection, and the like.

  The controller 23 includes room temperature detecting means for detecting the room temperature, room temperature setting means for setting the target room temperature, and liquid temperature setting means for setting the temperature of the liquid heat medium. The liquid temperature setting means is operated at a fixed liquid temperature for operation at a fixed liquid temperature, and according to the heating load estimated from the set room temperature and the current room temperature. When the load is small, it is possible to switch to the liquid temperature automatic operation in which the liquid temperature is automatically varied so as to operate at a low liquid temperature.

  The control means 9 is connected to the controller 23 installed in the room by wireless or wired so that bidirectional communication is possible. The control means 9 includes information on the set room temperature, the current room temperature and the set liquid temperature from the controller 23, the forward liquid temperature detection means 7 for detecting the liquid heat medium temperature at the outlet of the refrigerant-liquid heat exchanger 4, and the indoor radiator. The output of the return liquid temperature detecting means 8 for detecting the return liquid temperature from 22 is taken in as control information. The control means 9 controls the circulation pump 6, the compressor 3, the heat source side blower fan 1 and the like of the heat pump heat source unit 21 based on these control information.

  FIG. 2 is a schematic diagram of the Mollier diagram showing the characteristics of the refrigerant. The upper symbol CP in FIG. 2 indicates the critical point of the refrigerant, and the line connected by the symbols ABCD indicates the state of the refrigeration cycle. In the embodiment of the present invention, as shown in FIG. 2, a refrigeration cycle not exceeding the critical point is formed, and the amount of heat exchanged between the symbols B and C with the liquid on the use side in the refrigerant-liquid heat exchanger 4 Become. Here, in order to generate a high-temperature liquid exceeding 60 ° C., which is equivalent to that of a petroleum boiler, it is necessary to use a refrigerant condensing temperature higher than the required liquid temperature 60 ° C., so the temperature of the critical point CP is necessary. A refrigerant having a liquid temperature higher than 60 ° C. and having a temperature of about 70 ° C. or higher is used, but here the refrigerant composition is not particularly mentioned.

  Next, the control operation of the liquid circulation heating system 100 according to the embodiment of the present invention will be described based on the flowcharts shown in FIGS. 3 and 4.

  In FIG. 3, when any of the controllers 23 of the indoor radiator 22 is started to operate in step S1, the operation start information, set room temperature, current room temperature, set liquid temperature information (liquid temperature) are sent to the control means 9 of the heat pump heat source unit 21. In the case of the fixed operation, an arbitrary liquid temperature set by the controller 23 is transmitted, and in the case of the liquid temperature automatic operation, information that the liquid temperature automatic operation is selected is transmitted.

  Next, in step S2, the control means 9 gives a speed command so that the circulating pump 6 operates at the initial rotational speed stored in advance in the control means 9, and the compressor 3 so that the outgoing liquid water temperature becomes the target liquid temperature. Control the number of revolutions. Details of the control of the rotation speed of the compressor 3 will be described later with reference to FIG. Note that the initial rotational speed is not constant and may be varied according to the target outgoing liquid water temperature.

  Next, the forward liquid temperature is detected by the forward liquid temperature detection means 7 in step S3.

  Next, the return liquid temperature is detected by the return liquid temperature detection means 8 in step S4.

  Next, in step S5, the difference between the return liquid temperature detected in step S3 and the return liquid temperature detected in step S4 (ΔTa) (forward liquid temperature−return liquid temperature) is the return liquid temperature. It is determined whether the temperature difference is equal to or higher than the lower limit of temperature difference (ΔTaL: first threshold).

  When the return liquid temperature difference (ΔTa) is less than the return liquid temperature difference lower limit (ΔTaL) (step S5: No), the process proceeds to step S8 to perform a process of reducing the rotational speed of the circulation pump 6 by a predetermined rotational speed. . Here, the back and forth liquid temperature difference lower limit (ΔTaL) is the minimum temperature difference necessary to improve the efficiency of the heat pump.

  When the return liquid temperature difference (ΔTa) is equal to or larger than the return liquid temperature difference lower limit (ΔTaL) in step S5 (step S5: Yes), the process proceeds to step S6. In step S6, it is determined whether or not the return liquid temperature difference (ΔTa) is less than or equal to the upper limit of the return liquid temperature difference (ΔTaH: second threshold). Here, when the return liquid temperature difference (ΔTa) exceeds the upper limit of the return liquid temperature difference (ΔTaH) (step S6: No), the process proceeds to step S9 to increase the rotational speed of the circulation pump 6 by a predetermined rotational speed. I do.

  When the return liquid temperature difference (ΔTa) is equal to or less than the return liquid temperature difference upper limit (ΔTaH) (step S6: Yes), the process proceeds to step S7, and the current rotational speed of the circulation pump 6 is maintained. The upper limit of the return liquid temperature difference (ΔTaH) is the maximum temperature difference that can be tolerated in order that the indoor radiator 22 does not have a shortage of heat dissipation due to a decrease in flow rate.

  The return liquid temperature difference lower limit (ΔTaL) and the return liquid temperature difference upper limit (ΔTaH) are determined by the heat dissipation characteristics of the indoor radiator 22, and no specific values are mentioned here. When the return liquid temperature difference (ΔTa) is too large, the circulation flow rate of the liquid on the use side is insufficient and the capacity of the indoor radiator 22 is insufficient. Conversely, when the return liquid temperature difference (ΔTa) is too small, the use-side liquid circulation flow rate is excessive, and the use-side liquid is being conveyed to the indoor radiator 22 more than necessary. The control flow shown in FIG. 3 explains the control for correcting these conditions.

  Next, the flowchart of FIG. 4 will be described.

  In FIG. 4, when any of the controllers 23 of the indoor radiator 22 is started to operate in step S <b> 11, operation start information, set room temperature, current room temperature, set liquid temperature information (liquid temperature In the case of the fixed operation, an arbitrary liquid temperature set by the controller 23 is transmitted, and in the case of the liquid temperature automatic operation, information that the liquid temperature automatic operation is selected is transmitted.

  Next, in step S <b> 12, the control unit 9 gives an operation command so that the compressor 3 operates at the initial rotational speed stored in advance in the control unit 9.

  Next, in step S13, the forward liquid temperature detecting means 7 detects the forward liquid temperature (Ta).

  Next, in step S14, the forward liquid temperature (Ta) is compared with the target forward liquid temperature (Ttgt). When the outgoing liquid temperature (Ta) is lower than the target outgoing liquid temperature (Ttgt-α) (Ta <Ttgt-α), the process proceeds to step S15, and a process of increasing the rotational speed of the compressor 3 by a predetermined rotational speed is performed.

  In step S14, when the forward liquid temperature (Ta) exceeds the target forward liquid temperature (Ttgt + α) (Ta> Ttgt + α), the process proceeds to step S16, and a process for reducing the rotational speed of the compressor by a predetermined rotational speed. I do. The value obtained by adding or subtracting α (margin value) to (Ttgt) described above is for giving a range to the target value in order to converge the rotational speed control of the compressor 3.

  When the forward liquid temperature (Ta) is within the target forward liquid temperature (Ttgt) ± α in step S14 (Ttgt + α ≧ Ta ≧ Ttgt−α), the process proceeds to step S17, and the current state of the compressor 3 is reached. Maintain speed.

  The target forward liquid temperature (Ttgt) (set temperature) is the liquid temperature set by the controller 23 when the liquid temperature is fixed, the set room temperature when the liquid temperature is automatic, and the liquid temperature calculated from the current room temperature information. . The upper and lower limits of the temperature range to be set are not defined, but at least the upper limit temperature can be set up to 60 ° C to 70 ° C, which is a temperature range that can be generated by the boiler.

  As described above, in the present embodiment, a refrigerant having a high critical temperature capable of generating as high a temperature as that of an oil boiler is used, and the target liquid temperature (Ttgt) is set within a range not exceeding the critical temperature. The rotational speed of the compressor 3 is controlled so that it becomes. At the same time, the temperature within a certain range where the difference between the return temperature, which is the temperature difference between the temperature of the liquid on the use side that is exchanged with the refrigerant on the heat source side and sent to the radiator, and the temperature of the liquid returned from the radiator The circulation flow rate is adjusted by controlling the rotational speed of the circulation pump 6 so that This makes it possible to generate high-temperature water exceeding 60 ° C. as the use-side liquid without causing the indoor radiator 22 due to a decrease in flow rate to cause a shortage of heat dissipation and without reducing the efficiency of the heat pump cycle.

  Furthermore, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent requirements.

  For example, even if some constituent elements are deleted from all the constituent elements shown in each of the above embodiments, the problem described in the column of the problem to be solved by the invention can be solved, and described in the column of the effect of the invention. In the case where the obtained effect can be obtained, a configuration in which this configuration requirement is deleted can be extracted as an invention. Furthermore, you may combine the structural requirements in the said embodiment suitably.

  As described above, the liquid circulation heating system according to the present invention is useful for a heat pump type hot water heating system that uses a heat pump as a heat source for heating a liquid, and in particular, without reducing the efficiency of the heat pump cycle. It is suitable for a liquid circulation heating system that generates high temperature and stability.

DESCRIPTION OF SYMBOLS 1 Heat source side ventilation fan 2 Heat source side heat exchanger 3 Compressor 4 Refrigerant-liquid heat exchanger 6 Circulation pump 7 Forward liquid temperature detection means 8 Return liquid temperature detection means 9 Control means 10 Refrigerant flow rate adjustment valve 21 Heat pump heat source machine 22 Indoor Radiator 23 Controller 24 Connection piping 100 Liquid circulation heating system S1 to S9, S11 to S17 Steps

Claims (4)

A compressor that circulates refrigerant on the heat source side and adjusts the circulation flow rate;
A circulation pump that circulates liquid through a radiator installed in the room and adjusts the circulation flow rate;
A heat exchanger for exchanging heat between the refrigerant and the liquid;
Forward liquid temperature setting means for setting a set temperature of the temperature of the liquid to be sent to the radiator;
Outward liquid temperature detection means for detecting the temperature of the liquid sent to the radiator,
Return liquid temperature detection means for detecting the temperature of the liquid returned through the radiator,
With
The circulating pump adjusts the circulating flow rate of the liquid so that the difference between the temperatures detected by the forward liquid temperature detecting means and the return liquid temperature detecting means falls within a desired range;
The liquid circulation heating system, wherein the compressor adjusts the circulation flow rate of the refrigerant so that the temperature detected by the forward liquid temperature detection means falls within a desired range including the set temperature. If the temperature difference is less than the first threshold, reduce the number of revolutions of the circulation pump,
The liquid circulation heating system according to claim 1, wherein when the temperature difference is greater than a second threshold value that is greater than a first threshold value, the number of revolutions of the circulation pump is increased. If the temperature detected by the forward liquid temperature detection means is lower than the temperature lower than the set temperature by a margin value, increase the rotational speed of the compressor,
3. The liquid circulation heating according to claim 1, wherein when the temperature detected by the forward liquid temperature detection unit is higher than a temperature higher than the set temperature by a margin value, the rotational speed of the compressor is decreased. system. The liquid circulation heating system according to claim 1, 2 or 3, wherein the refrigerant has a critical temperature of 70 ° C or higher and is circulated while being maintained at a temperature lower than the critical temperature.

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