JPH07190547A - Controller for heat pump type hot water supplying apparatus - Google Patents

Abstract

PURPOSE:To operate in a high efficiency with high coefficient of performance by conducting a single stage compressing cycle operation using a multi-circuit type in an area having a low supply hot water temperature corresponding to a boiled supply hot water temperature of a water side tube inlet at a heat exchanger for supplying hot water. CONSTITUTION:A control signal is fed according pieces of information of a signal receiving circuit and a superheat degree calculator by a compressor frequency calculator and an expansion valve opening calculator to control a frequency of a refrigerant two-stage compressor 2a and openings of first, second and third expansion valves 4a, 4b, 4c. A differential temperature between an inlet temperature of a water side tube 3c and a first predetermined temperature is calculated by a differential temperature calculator, transmitted to the signal receiving circuit from a signal transmitter, and an operation switching control signal is sent. First, second and third solenoid valves 7a, 7b, 7c are controlled in response to a final boiling temperature, i.e., the inlet temperature of the tube 3c of a hot water supplying heat exchanger 3a. Thus, a single-stage compressing cycle operation and a two-stage compressing cycle operation are switched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump water heater control system.

[0002]

2. Description of the Related Art A conventional heat pump water heater has a structure in which hot water is supplied by using a refrigerant two-stage compressor as shown in FIG.

The conventional heat pump type water heater will be described below with reference to the drawings.

FIG. 4 is a refrigeration cycle diagram of a conventional heat pump water heater. The flow of the refrigeration cycle circuit when performing a single-stage compression cycle operation in this heat pump type hot water supply device is that the refrigerant side pipe 3b of the hot water supply heat exchanger 3a from the refrigerant two-stage compressor 2a, the first expansion valve 4a, the intermediate heat exchange. It is a circulation path that returns to the refrigerant two-stage compressor 2a via the device 6, the third expansion valve 4c, and the heat source side heat exchanger 5. The flow of the refrigeration cycle in the two-stage compression cycle operation is as follows: the refrigerant two-stage compressor 2a, the refrigerant side pipe 3b of the hot water supply heat exchanger 3a, the first expansion valve 4a.
Through the second expansion valve 4b and a part of the intermediate heat exchanger 6
Passing through the second compression section 2c, and partly through the intermediate heat exchanger 6 through the third expansion valve 4c, the heat source side heat exchanger 5 and back to the suction of the first compression section 2b. There is.

Refrigerant is the refrigerant side pipe 3 of the hot water supply heat exchanger 3a.
Condensation heat is released while passing through b, heat exchange is performed with water passing through the water side pipe 3c, and the water side outlet temperature of the water side pipe 3c detected by the water side outlet temperature sensor 12 corresponds to the water side outlet temperature. ,
The single-stage compression cycle operation and the two-stage compression cycle operation were switched by opening and closing the first, second and third solenoid valves 7a, 7b and 7c. On the other hand, in the water supply circuit, the water circulation amount is adjusted by adjusting the valve of the water supply valve 11, but hot water is pumped up from the hot water storage tank 9 by the water circulation pump 10, and the refrigerant gas and heat are supplied to the water side pipe 3c of the hot water heat exchanger 3a. It is formed by a circulation path that is exchanged and returns to the hot water storage tank 9.

[0006] In the prior art, the hot water supplied to the hot water supply heat exchanger 3a by the single-stage compression cycle operation exchanges heat with the refrigerant gas in only one circulation here, and the single-stage compression cycle operation and the second-stage compression cycle are performed. The outlet temperature of the water side pipe 3c is raised to a first predetermined temperature optimum for switching the operation and stored in the hot water storage tank 9, and then the water supply valve 14 is squeezed to reduce the water circulation to perform the two-stage compression cycle operation. The heat was exchanged with the refrigerant gas in the hot-water supply heat exchanger 3a by switching only once again, and was boiled to the final boiling temperature and stored in the hot water storage tank 9. Therefore, the hot water is boiled from the initial temperature to the final boiling temperature by the single circulating water method, and especially from the initial temperature to the first predetermined temperature, the refrigeration cycle performs the single-stage compression cycle operation, and the first predetermined temperature to the final temperature. A two-stage compression cycle operation was performed up to the boiling temperature.

[0007]

However, in the conventional heat pump type hot water supply apparatus as described above, in the single-stage compression cycle operation by the single circulating water system, the water side outlet of the water side outlet is supplied through the hot water supply heat exchanger with only one circulation. Since the water temperature is raised to the first predetermined temperature, the amount of water circulation in the hot water supply heat exchanger is also throttled and the boiling water supply amount per unit time is reduced, resulting in poor efficiency.
When the first predetermined temperature is maintained in single-stage compression, the condensation temperature on the refrigeration cycle side must be maintained at the first predetermined temperature or higher, that is, the condensation pressure increases together with the condensation temperature, and thus the compressor has a high compression ratio. Therefore, there is a problem that the lubricating oil deteriorates and the piston part is damaged, and the compressor efficiency and the coefficient of performance (ratio of the compressor input to the capacity of the hot water heat exchanger) decrease.

The present invention has been made to solve the above problems.

[0009]

Means for Solving the Problems In order to solve the above problems, the following means were taken.

That is, in the control system of the heat pump type hot water supply apparatus, the hot water supply temperature at which the switching between the single-stage compression cycle operation and the two-stage compression cycle operation is optimal, that is, the boiling water supply temperature in the water side cycle, The operation switching point that enables cycle operation with a high coefficient of performance (ratio of compressor input to capacity of hot water heat exchanger) is always the first predetermined temperature, and the hot water supply temperature at the water side inlet is the first hot water temperature. In the region lower than the predetermined temperature, the condensing temperature and the condensing pressure are also low, the single-stage compression cycle operation having a higher coefficient of performance than the two-stage compression cycle operation is performed, and the temperature until the final boiling hot water temperature becomes higher than the first predetermined temperature. In the region, the condensation temperature and the condensation pressure are high, and the two-stage compression cycle operation having a higher coefficient of performance than the single-stage compression cycle operation is performed,
The single-stage compression cycle operation and the two-stage compression cycle operation are switched so that a high coefficient of performance can always be maintained.In the single-stage compression cycle operation, the hot water tank transfers the hot water supply heat exchanger to the hot water supply heat exchanger. It is circulated and boiled by using a multi-circulation water system in which the process of sending and exchanging heat with the refrigerant gas and returning to the hot water storage tank is performed a plurality of times to gradually raise the hot water supply temperature to the first predetermined temperature. After reaching the first predetermined temperature, the refrigeration cycle side is switched to the two-stage compression cycle operation by the operation switching control means as in the conventional case, and the heat exchange with the refrigerant gas is performed only once in the hot water heat exchanger. Then, the one circulating water system is used in which the temperature is raised to the final boiling temperature.

[0011]

According to the present invention, the following actions are brought about by the above means.

That is, unlike the prior art, by increasing the hot water supply temperature stepwise to the first predetermined temperature in the single-stage compression cycle operation by the multi-circulation water system, the operation at a high compression ratio becomes short and the compression is shortened. In addition to protecting the inside of the machine, the operation was performed with a higher coefficient of performance than the conventional single-stage compression cycle operation using one circulating water system, and overall higher energy efficiency was achieved.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cycle configuration of a heat pump water heater according to an embodiment of the present invention. As shown in the drawing, 1 is an outdoor unit having a refrigerant two-stage compressor 2a configured to have a first compression section 2b and a second compression section 2c connected in series with the first compression section 2b, and 3a is a refrigerant side. A heat exchanger for hot water supply having a pipe 3b and a water side pipe 3c, 4a is a first expansion valve,
Reference numeral 4b is a second expansion valve, 4c is a third expansion valve, 5 is a heat source side heat exchanger, 6 is an intermediate heat exchanger, and 7a is a first electromagnetic control for switching between single-stage compression cycle operation and two-stage compression cycle operation. 7b is a second solenoid valve provided on the suction side of the first compression section, 7c is a third solenoid valve provided on the discharge side of the second compression section, and 8a and 9a are on the first compression section 2b. A temperature sensor and a pressure sensor that detect the temperature and pressure on the suction side, and 8b and 9b are a temperature sensor and a pressure sensor that detect the temperature and pressure on the suction side of the second compression unit 2c. Reference numeral 10 is a tank unit, 11 is a hot water storage tank, 12 is a water circulation pump, 13a is a temperature sensor for measuring the outlet temperature of the water side pipe 3c in the hot water supply heat exchanger 3a, and 13b is the inlet temperature of the water side pipe 3c. Temperature sensor, and 14 is a water supply valve. The flow of the refrigeration cycle and the water supply circuit are the same as the conventional ones, and are omitted here. Next, a block diagram of the refrigeration cycle control device is shown in FIG. Water side pipe 3c of heat exchanger 3a for hot water supply
After passing the inlet / outlet temperature of the water through the hot water supply temperature detection circuit 14, the temperature difference is calculated by the temperature difference calculation circuit 15, and the water supply valve opening control signal is sent and also sent to the signal sending circuit 16 and from 16 to the signal receiving circuit 17. Send. On the other hand, at the temperatures and pressures detected by the suction temperature sensors 8a and 8b and the suction pressure sensors 9a and 9b of the first compression unit 2b and the second compression unit 2c, respectively, the temperature passes through the suction temperature detection circuit 21 and the superheat degree calculation circuit 20. The pressure is sent from the suction pressure detection circuit 23 to the saturation temperature calculation circuit 22, and the superheat degree in the suction of the refrigerant two-stage compressor 2a is calculated through the superheat calculation circuit 20. Based on the information of the signal receiving circuit 17 and the superheat degree calculating circuit 20, the compressor frequency calculating circuit 18 and the expansion valve opening calculating circuit 19 calculate and send out the compressor frequency control signal and the expansion valve opening control signal. The frequency of the two-stage compressor 2a and the expansion valve openings of the first expansion valve 4a, the second expansion valve 4b, and the third expansion valve 4c are controlled.

Further, the temperature difference between the inlet temperature of the water side pipe 3c and the first predetermined temperature is calculated by the temperature difference calculating circuit 15 and transmitted from the signal transmitting circuit 16 to the signal receiving circuit 17 to transmit the operation switching control signal. To do. In this heat pump type water heater,
The final boiling temperature, that is, as shown in (Table 1), the first solenoid valve 7a, the second solenoid valve 7b, and the third solenoid valve 7c are controlled according to the inlet temperature of the water side pipe 3c of the hot water supply heat exchanger 3a. This switches between single-stage compression cycle operation and two-stage compression cycle operation.

[0015]

[Table 1]

FIG. 3 compares the coefficient of performance between the single-stage compression cycle operation and the two-stage compression cycle operation with respect to the boiling hot water supply temperature in the hot water supply heat exchanger.

In this heat pump water heater, the optimum cycle temperature for switching the cycle operation (first predetermined temperature) is 50 ° C. and the final boiling water temperature is 80 ° C., as shown in FIG. First, in Fig. 3, in the single-stage compression cycle operation at a hot water supply temperature of 50 ° C or less, the coefficient of performance when the hot water supply temperature is boiled to 20 ° C is point a, and the coefficient of performance at the temperature when boiled to 30 ° C is the coefficient of performance. B point, the coefficient of performance when boiled to 40 ℃, c point,
If the coefficient of performance when heated to 50 ° C is d point, d
The point is also the first predetermined temperature, but the hot water supply temperature is 10 to 50 ° C
In the region of 1, the condensing pressure is low because of the low condensing temperature, and the compression reduction ratio is low, and the coefficient of performance is higher in the single-stage compression cycle with a low compression ratio and higher compressor efficiency than in the two-stage compression cycle. However, when the hot water supply temperature is 40 to 50 ° C, the compression ratio increases with the condensing temperature, and the coefficient of performance of the single-stage compression cycle decreases significantly. When the boiling hot water supply temperature reaches 50 ° C, compression is performed at a high compression ratio. It intersects with a highly efficient two-stage compression cycle.

Therefore, if this 50 ° C. is set as the optimum operation switching point and the operation is switched from the single-stage compression cycle operation to the two-stage compression cycle operation, the operation can be performed with a high coefficient of performance. That is, the coefficient of performance is higher in the single-stage compression cycle operation than in the two-stage compression cycle operation in the low compression ratio range where the boiling hot water supply temperature is lower than the first predetermined temperature 50 ° C. The condensing temperature and condensing pressure are high in the region of high compression ratio up to the final boiling hot water supply temperature of 80 ° C, which is higher than 50 ° C, and the coefficient of performance is higher in the two-stage compression cycle operation than in the single-stage compression cycle operation. Become. As shown in FIG. 3, when the cycle operation is switched at the first predetermined temperature of 50 ° C. where the single-stage compression cycle curve and the second-stage compression cycle curve intersect, a high coefficient of performance is always maintained for the boiling hot water temperature. While it is possible to perform cycle operation. Therefore, the hot water supply heat exchanger 3 is adjusted by adjusting the water supply valve 14.
The water circulation amount in a is controlled, and further, the inlet temperature 13b of the water side pipe 3c is switched to the two-stage compression cycle operation from the single-stage compression cycle operation at the first predetermined temperature of 50 ° C. (Table 2), (Table 3).
I will drive in this mode. That is, the water side pipe 3
When the inlet hot water temperature of c is 50 ° C or lower, the solenoid valve 7a is closed,
When 7b and 7c are opened for single-stage compression cycle operation and the inlet hot water temperature of the water side pipe 3c is 50 ° C or higher, the solenoid valve 7
All of a, 7b, and 7c are opened, the water supply valve 14 is throttled, and the two-stage compression cycle operation is performed.

[0019]

[Table 2]

[0020]

[Table 3]

In the water supply circuit at this time, as shown in (Table 2), in the single-stage compression cycle operation, the valve opening of the water supply valve 14 and the frequency of the compressor are controlled so that the inlet / outlet temperature difference of the water side pipe 3c is suppressed to 10 ° C. or less. The refrigerant side pipe 3b and the water side pipe 3c exchange heat repeatedly via the hot water supply heat exchanger 3a,
The outlet hot water supply temperature of the water side pipe 3c is 20 ° C, 30 ° C, 40 ° C.
And a multi-circulation water system in which the final temperature is raised to 50 ° C in four times. After the inlet hot water supply temperature of the water side pipe 3c reaches 50 ° C., heat is exchanged with the refrigerant through the hot water supply heat exchanger 3a through only one efficient circulation, and the final boiling hot water supply temperature of 80 ° C. As shown in (Table 3), the valve opening of the water supply valve 14 and the compressor frequency are controlled so that the inlet / outlet temperature difference of the water side pipe 3c can be maintained at 30 ° C.

Therefore, as described above, the hot water supply temperature is low 10
In the range of up to 50 ° C, the coefficient of performance at each temperature in Fig. 3 is a, b, and c by dividing the temperature into 10 ° C and boiling up to 50 ° C as shown in (Table 2) by the multiple circulating water system.
At point d, especially at a hot water supply temperature of 20 to 40 ° C, the compression ratio is low, the capacity efficiency of the compressor is high, and the amount of refrigerant circulating in the condenser is increased, so that the hot water supply capacity is increased, and operation in a state with a high coefficient of performance is achieved. It has become possible. Also, by using the multi-circulation water system, the hot water supply temperature is 50 ° C, which has a low coefficient of performance.
The operating time at point d was shortened, and the hot water could be boiled from the initial temperature of 10 ° C to 50 ° C in a short time. If the single-stage compression cycle operation by the conventional single circulating water system is performed here, the hot water supply temperature from the initial temperature of 10 ° C to 50 ° C is boiled up at the point d where the hot water supply capacity is low and the coefficient of performance is low. In the hot water supply operation at the point d, the water circulation capacity is reduced because the hot water supply capacity is reduced, and it takes a lot of time to boil the hot water supply water at 50 ° C.
Therefore, the coefficient of performance is improved by performing the single-stage compression cycle operation by the multi-circulation water method, and after the first predetermined temperature is reached, by performing the two-stage compression cycle operation by the single circulation water method, a high compression ratio is achieved. It is possible to provide a heat pump type water heater that can shorten the operation time of the single-stage compression cycle, protect the interior of the compressor, and operate with high efficiency. still,
(1) Although the expansion valve is used here as the pressure reducer, other pressure reducing devices may be used.

(2) Although the solenoid valve is used as the cycle operation switching device, another switching device may be used.

(3) In the single-stage compression cycle operation by the multi-circulation water system, the boiling water temperature was raised from 10 ° C to 50 ° C in 10 ° C increments, and the boiling temperature was raised 4 times. Not limited.

(4) The setting of the first predetermined temperature, which is the optimum operation switching point for switching between the single-stage compression cycle operation and the two-stage compression cycle operation, may be switched at any other temperature.

[0026]

As described above, the heat pump type water heater according to the embodiment of the present invention corresponds to the boiling hot water supply temperature at the inlet of the water side pipe in the heat exchanger for hot water supply, and is high in the low hot water temperature range. By performing a single-stage compression cycle operation using the circulating water method, it is possible to realize an efficiency-efficiency operation with a high coefficient of performance, which was not possible with conventional technology, and in addition, in the high compression ratio region where the boiling water temperature is high. The operating time was shortened, and problems such as deterioration of the lubricating oil of the compressor and damage to the bearings could be resolved and the interior of the compressor could be protected. Also, from the optimum switching point temperature (first predetermined hot water temperature) for switching between single-stage compression cycle operation and two-stage compression cycle operation, the single circulating water system was used as before until the final temperature. The heat exchange rate between the refrigerant and the hot water is improved by performing a single-stage compression cycle operation using the multi-circulation water method and a single-stage compression cycle operation using the single-circulation water method, depending on the hot water supply temperature. It became possible to boil water, and it was possible to provide a heat pump water heater that realizes a refrigeration cycle with high energy efficiency.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram in an embodiment of a heat pump water heater of the present invention.

FIG. 2 is a control block diagram of a compressor frequency and an electric expansion valve, a solenoid valve, and a water supply valve in the refrigeration cycle control device of the embodiment.

FIG. 3 is a diagram showing the relationship between the coefficient of performance and the boiling hot water temperature in the single-stage compression cycle operation and the two-stage compression cycle operation.

FIG. 4 is a refrigeration cycle diagram of a conventional heat pump water heater.

[Explanation of symbols]

 1 Outdoor Unit 2a Refrigerant Two-Stage Compressor 2b First Compressor 2c Second Compressor 3a Hot Water Heat Exchanger 3b Refrigerant Side Pipe 3c Water Side Pipe 4a First Expansion Valve 4b Second Expansion Valve 4c Third Expansion Valve 5 Heat Source Side heat exchanger 6 Intermediate heat exchanger 7a First solenoid valve 7b Second solenoid valve 7c Third solenoid valve 8a First compression unit suction temperature sensor 8b Second compression unit suction temperature sensor 9 Tank unit 10 Water storage tank 11 Water circulation pump 12a Water side inlet temperature sensor 12b Water side outlet temperature sensor 13 Water supply valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Murozono 1006, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. Heat exchange between a refrigerant two-stage compressor having a first compression part and a second compression part, the capacity of which is variable, and a refrigerant gas compressed by the two-stage refrigerant compressor and a water side cycle. A heat exchanger for hot water supply, a decompressor, and an evaporator are connected to form a refrigeration cycle, and a single-stage compression cycle for operating either one of the first compression section and the second compression section, the first compression section and Operation switching control means for switching between a two-stage compression cycle in which the second compression section is connected in series and operated simultaneously, and a parallel compression cycle in which the first compression section and the second compression section are connected in parallel and operated simultaneously. On the other hand, a hot water storage tank, a water circulation pump, and water circulation amount control means for controlling the amount of water circulation in the heat exchanger for hot water supply, which are sequentially connected to form a water side cycle. The first temperature detection to detect the temperature of the water side inlet and the temperature of the outlet Means and second temperature detecting means, first refrigerant state detecting means and second refrigerant state detecting means for detecting the state of the refrigerant at the suction of the first compression part and the second compression part, and the decompression ratio of the decompressor. And a capacity control means for controlling the capacity of the refrigerant two-stage compressor, and a difference for calculating the temperature difference between the water side inlet and the outlet detected by the first and second temperature detecting means. A temperature arithmetic circuit is provided, and a superheat degree arithmetic circuit for calculating the superheat degree in the suction of the compression section from the first and second refrigerant state detecting means is provided, and the capacity of the compressor and the water circulation amount are calculated according to the respective arithmetic results. The single-stage compression is performed on the refrigeration cycle side until the temperature of the water side inlet detected by the first temperature detecting means reaches a first predetermined temperature located between the initial temperature and the final boiling temperature. Cycle luck The water introduced into the hot water supply heat exchanger is sent from the hot water storage tank to the hot water supply heat exchanger by the water circulation pump, exchanges heat with the refrigerant gas, and is returned to the hot water storage tank a plurality of times. The water side inlet temperature is circulated using a multi-circulation water system in which the water side inlet temperature is raised stepwise to the first predetermined temperature, and after the water side inlet temperature reaches the first predetermined temperature, the refrigeration cycle side performs the above operation. The switching control means switches to the two-stage compression cycle operation, and the water introduced into the hot water supply heat exchanger exchanges heat with the refrigerant gas in only one circulation in the hot water supply heat exchanger to raise the final boiling temperature. A control device for a heat pump water heater, which circulates using one circulating water system.