JPS6146833A - Method for controlling air heat source thermal recovery type heat pump - Google Patents

Abstract

PURPOSE:To provide an efficient operation and save energy by a method wherein a compressor is controlled to a lower capacity side only when a hot water temperature is less than the desired value in case that an evaporator cooling pump and an air heat exchanger are set to a thermal recovery requiring condition during their operation and then the condensor hot water pump is operated. CONSTITUTION:When all the condensed heat is radiated by an air heat exchanger 14 and a thermal recovery requiring signal is outputted during a cooling operation, a hot water temperature in the condensor 3 sensed by a temperature sensor 17 is less than the desired value, an amount of coolant gas sucked into the compressor 1 by a vane motor is set to a low capacity side. With this arrangement, low temperature water is flowed into the condensor 3 and even if a rapid decrease of the discharging pressure is found, a decrease in sucking pressure of the compressor 1 is restricted, an operation of the protective relay is prevented and an efficient operation and a saving of energy can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling an air source heat recovery type heat pump.

(Prior Art) A conventional air source heat recovery type heat pump has a system diagram as shown in FIG. That is, the heat pump includes a compressor 1, an evaporator 2, a condenser 3, a first expansion valve 4, and the like. The evaporator 2 is connected to the cooling load side directly or via the cold water tank 5 and cold water piping 6.7. A cold water pump 8 is interposed in one of the cold water pipes 7 .

The condenser 3 is connected either directly to the heating load or to the hot water tank 9 via hot water pipes 10.11. One hot water pipe 1
0 is equipped with a hot water pump 12.

Moreover, 13 in the figure is a three-way valve that switches and supplies the refrigerant gas from the compression ii to the evaporator 2, the condenser 3, and the air heat exchanger 14. A check valve 15 is interposed between the air heat exchanger 14 and the condenser 3 to allow the refrigerant gas from the heat exchanger 14 to flow only to the condenser 3 side. A second expansion valve 16 is provided in parallel with this check valve 15 . The air source heat recovery type heat pump cannot be used without a chilled water load. Therefore, in order to control the capacity of the chilled water load, the temperature of the chilled water at the outlet of the evaporator 2 is detected, and the compressor 1 is controlled to perform turbo compression via a temperature controller (not shown) so that the temperature remains constant. In this case, capacity control is performed by adjusting the amount of refrigerant gas sucked into the compressor 111 by a vane motor (not shown) as a capacity control mechanism provided in the suction section. When the compressor 1 is a screw compressor, a slide valve is used instead of the vane motor, and when the compressor 1 is a reciprocating compressor, an unloader mechanism is used instead of the vane motor.

Next, the operation of the conventional heat pump shown in FIG. 2 will be explained.

■Heating operation: First, switch the three-way valve 13 to the evaporator 2 and air heat exchanger 14 side, and with the hot water pump 12 operating, refrigerant gas compressed to high temperature and high pressure is supplied from the compressor 1 to the condenser 3. supply,
A hot water tank 9 that condenses and liquefies refrigerant gas and circulates it through the condenser 3
Heat the hot water from.

The liquefied refrigerant is supplied to the second expansion valve 16 for adiabatic expansion, further supplied to the air heat exchanger 14 to be evaporated and gasified, and returned to the compressor 1 through the three-way valve 13.

■Cooling operation when there is a heating load; First, connect the three-way valve 13 to compressor 1, air heat exchanger 1, compressor 1
The refrigerant gas compressed to high temperature and high pressure is supplied to the air heat exchanger 14 through the three-way valve 13, where it radiates heat, condenses, and liquefies it. The liquefied refrigerant is supplied to the first expansion valve 4 through the check valve 16 and the condenser 3, where it is adiabatically expanded, and further supplied to the evaporator 2, where it is evaporated, gasified, and circulated through the evaporator 2. The cold water from the cold water tank 5 is cooled. After this, the gasified refrigerant returns to compression l1111.

■ Simultaneous operation of cooling and heating; First, switch the three-way valve 13 to the evaporator 2 and air heat exchanger 14 side, and with the hot water pump 12 and cold water pump 8 operating, the compressor 1 compresses the air to high temperature and high pressure. The refrigerant gas is supplied to the condenser 3, the refrigerant gas is condensed and liquefied, and the hot water from the dry water tank 9 circulating through the condenser 3 is heated. The liquefied refrigerant is supplied to the first expansion valve 4 for adiabatic expansion, and further supplied to the evaporator 2 where it is evaporated and gasified to cool the cold water from the cold water tank 5 that circulates through the evaporator 2. After this, the gasified refrigerant returns to the compressor 1.

By the way, during the above-mentioned cooling operation, the heat recovery "required" signal is issued, the hot water pump 12 is operated, and the above-mentioned
In some cases, a heating cycle is executed to recover heat.

[Problem that the invention seeks to solve]

However, when the heat recovery required signal is issued during the cooling operation of the heat pump described above and the drought pump 12 is operated, if the hot water temperature on the hot water tank 9 side including the hot water piping 10 is low, the hot water will condense. At this time, during cooling operation, the discharge pressure of the compressor 1 is normally 18 atC1 (
However, due to the inflow of the low-temperature hot water, the pressure suddenly drops to about 9 at (l), and the suction pressure of the compressor 1 decreases, causing the low-pressure protection of the protection device to drop. The relay operates and the heat pump automatically stops.To avoid this, either manually stop the heat pump when switching the operation, then operate the hot water pump 12 and then operate the heat pump again, or operate the hot water pump at all times. The efficiency is low, and there is also a problem from the point of view of labor saving.In particular, when using cold water without a heat storage tank,
For buildings that employ so-called closed systems, where hot water is directly connected to the load, the interval time is short and operation management becomes even more troublesome.

The present invention can improve the efficiency of operation when switching from a cooling operation state to a state requiring heat recovery, and
The present invention aims to provide a control method for an air source heat recovery type heat pump that can achieve labor savings.

[Means for solving problems]

The present invention is an air source heat recovery type heat pump that detects the temperature on the hot water side when heat recovery is required while the evaporator cold water pump and air heat exchanger are in operation, and detects the temperature when the temperature is below a predetermined m. The feature is that the compressor capacity control mechanism is controlled to the low capacity side only when the condenser hot water pump is operated.

[Effect]

According to the above-mentioned method of the present invention, when heat recovery is required, the suction pressure of the compressor suddenly decreases due to the inflow of low-temperature hot water into the condenser, which eliminates the activation of the protection relay, thereby preventing the heat pump from operating. It is possible to smoothly switch from the cooling operation state to the heat recovery required state while operating the air conditioner, and as a result, as described above, it is possible to achieve operational efficiency and labor savings.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail with reference to FIG. Incidentally, members similar to those shown in FIG. 2 are designated by the same reference numerals and explanations thereof will be omitted.

In the heat pump system diagram of the present invention shown in FIG. 1, a temperature sensor 17 is provided in the hot water tank 9. The temperature sensor 17
is a vane motor (not shown) which is a capacity control l1 mechanism.
A sequence circuit is configured with the hot water at a predetermined temperature (for example, 2
5° C.) or lower, the compressor 1 is automatically operated to the lower capacity side.

Next, the control method of the present invention will be explained with reference to the system diagram shown in FIG.

When the heat pump is in operation and the air-conditioning operation is performed by dissipating all of the condensed heat through the air heat exchanger 14, when a heat recovery "required" signal is issued, the temperature sensor 17 detects the temperature on the hot water side of the condenser 3. The temperature is detected, and if the temperature is, for example, 25°C or lower, the amount of refrigerant gas sucked into the compressor 1 is adjusted by the vane motor (not shown) of the sequence circuit, and the compression 'l11 is set to the low capacity side. Operated automatically. As a result, the capacity of the heat pump decreases, the suction pressure increases slightly, and the discharge pressure decreases slightly. If the hot water pump 12 is operated in this state, even if low-temperature hot water flows into the condenser 3 and a sudden drop in discharge pressure occurs, the associated drop in suction pressure of the compressor 1 will be small and low pressure protection will be achieved. This can prevent the relay from operating. The operation inside the heat pump, from the "heat recovery required" signal to cooling operation, is processed by a timer, etc.

On the other hand, the hot water temperature detected by the temperature sensor 17 is a predetermined temperature (
25° C.), the hot water pump 12 is operated without operating the compressor 1 to the lower capacity side by the vane motor (not shown) which is the capacity side mall structure of the heat pump.

In addition, although the temperature sensor was provided in the hot water tank in the above example,
It is not limited to this, and it may be installed in hot water piping.

〔Effect of the invention〕

As detailed above, according to the present invention, when heat recovery is required, the suction pressure of the compressor suddenly decreases due to the flow of low-temperature hot water into the condenser, and the protection relay is activated. It is possible to provide a control method for an air-source heat recovery heat pump that can smoothly switch from a cooling operation state to a heat recovery required state while operating the heat pump by eliminating the above problems, and which can further improve operational efficiency and save labor. .

[Brief explanation of drawings]

FIG. 1 is a system diagram of an air source heat recovery type heat pump used in an embodiment of the present invention, and FIG. 2 is a system diagram of a conventional heat pump. 1... Compressor, 2... Evaporator, 3... Condenser, 4
．． 16... Expansion valve, 5... Cold water tank, 9... Hot water tank, 12... Hot water pump, 13... Three-way valve, 14...
・Air heat exchanger, 17...Temperature sensor. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 1

Claims (1)

[Claims] In an air source heat recovery heat pump, when heat recovery is required while the evaporator cold water pump and air heat exchanger are in operation, the temperature on the hot water side is detected, and the compressor is activated only if the temperature is below a predetermined value. A method for controlling an air-source heat recovery heat pump, comprising controlling a capacity control mechanism to a low capacity side to operate a condenser hot water pump.