JPH0214623B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for controlling the operation of an engine heat pump system mainly used for general air conditioning, greenhouse air conditioning, hot water supply, etc. An engine heat pump and a combustion-type auxiliary heat source device are arranged in series in the circulation flow path, and in low load areas only the engine heat pump is operated, and the engine speed is controlled in response to increases and decreases in the required load. This is an improved engine heat pump system operation control method that increases or decreases the capacity, operates the engine heat pump and auxiliary heat source device in parallel in high load areas that exceed the engine heat pump capacity, and controls the capacity of the auxiliary heat source device according to the required load. It is.

[Prior art]

Generally, a gas direct-fired absorption chilled/hot water unit,
Combustion-type auxiliary heat source devices such as gas burners and oil burners have a relatively large minimum capacity when ignited (for example, in a direct-fired absorption type cold/hot water unit, the minimum capacity is nearly 30% of the maximum capacity). ,
Therefore, as shown in Fig. 5, there is a normal low load area where only the engine heat pump is operated (capacity control area and rotation control area in the figure), and a high load area where the engine heat pump and auxiliary heat source device are operated in parallel. (Load control area in the diagram) There was a difference in capacity between the two.

[Problem to be solved by the invention] For this reason, when the required load fluctuates near the boundary between the low and high load regions, the auxiliary heat source device tends to start and stop frequently, and the fuel supply system of the auxiliary heat source device This resulted in early wear and tear of various equipment and ignition and extinguishing mechanisms. In addition, auxiliary heat source devices such as absorption-type cold/hot water units require standby time, resulting in a large amount of fuel loss due to repeated starting and stopping.

[Means to solve the problem]

The present invention is aimed at solving the problems found in conventional operation control, and is characterized by being based on the above-mentioned operation control method, and by controlling the supply to the load side. The engine speed is controlled based on the detection results of the temperature sensor to maintain the temperature of the heat transfer fluid at the set value, and the engine speed is controlled to decrease as the capacity increases gradually as the auxiliary heat source device starts up. It is in the point of doing.

[Effect]

According to the above operation control method, as shown in Fig. 4, the capacity characteristics of the entire system become linear, and the switching operation is performed between the operation state of only the engine heat pump and the parallel operation state of the engine heat pump and the auxiliary heat source device. hysteresis is given,
The frequency of starting and stopping of the auxiliary heat source device during operation near the boundary between the low load area and the high load area is reduced.

〔Effect of the invention〕

Therefore, early wear and tear of various devices in the fuel supply system of the auxiliary heat source device and the ignition/extinguishing mechanism is suppressed, and it has become possible to perform good operation for a long period of time with less maintenance. In addition, fuel loss due to frequent starting and stopping of the auxiliary heat source device is reduced, and smooth and stable operation that satisfies the required load can now be performed economically.

〔Example〕

Figure 1 shows a schematic configuration of the entire system used as air conditioning equipment, which basically consists of an engine heat pump 1, a combustion type auxiliary heat source device 2,
It consists of an indoor heat exchanger 3 and a pump 4 for forced circulation of hot water or cold water as a heat transfer fluid.

The engine heat pump 1 (hereinafter referred to as heat pump) includes a water-cooled gas engine 5 that uses city gas as fuel, a variable capacity refrigerant compressor 6 driven by the water-cooled gas engine 5, an expander 7 in the refrigerant cycle, Equipped with an outdoor air heat exchanger 8, a main heat exchanger 9, an auxiliary heat exchanger 10, and a heat exchanger 11 using exhaust gas, the engine speed control mechanism 12 controls the rotation speed and the capacity of the compressor 6 (adjusts the number of cylinders). ) allows the heating and cooling capacity of the heat pump 1 to be adjusted.

Furthermore, as the auxiliary heat source device 2, a gas direct-fired absorption cold/hot water unit using city gas as fuel is used, and this is equipped with a water cooling heat exchanger 13 and a cooling tower 14. .

Next, the heating and cooling operation mode of the above system will be explained. Note that mode switching is performed by switching a group of on-off valves provided in the flow path.

() Cooling operation mode (see Figure 2) Water as a heat medium fluid for cooling is transmitted through the heat-absorbing heat exchange part 2a of the cold/hot water unit 2 and the main body of the heat pump 1, as shown by the thick solid line flow path A in the figure. The room is cooled by cold water that is forcedly circulated by the pump 4 in the order of the heat exchanger 9 and the indoor heat exchanger 3, and cooled to a predetermined temperature in the heat exchange section 2a and the main heat exchanger 9.

The refrigerant of the heat pump 1 is circulated in the order of the compressor 6, the air heat exchanger 8 as a condenser, the expander 7, and the main heat exchanger 9 as an evaporator, as shown by the thick solid line flow path B in the figure. The air heat exchanger 8 radiates heat to the outside air, and the main heat exchanger 9 absorbs heat from the cooling circulating water.

In addition, by dividing the compressed refrigerant into the auxiliary heat exchanger 10 as a condenser, as shown by the thick broken line flow path B' in the figure, the water pumped by the auxiliary pump 15 is heated and flows. Hot water can be taken out from path C and used for various purposes.

Also, as shown by the thick solid line flow path D in the figure, the cooling water for the engine 5 is passed through the exhaust gas heat exchanger 11, the endothermic heat exchange section 2b of the cold/hot water unit 2, and the heat exchanger 13 of the cooling system in that order. The hot and cold water unit 2 is heated auxiliary using the high temperature water which is forcedly circulated by the pump 16 and absorbs the engine heat and then further absorbs heat by the exhaust gas heat exchanger 11. is returned and used for engine cooling.

In addition, the cooling water of the cold/hot water unit 2 flows through the heat exchange section 2c for heat radiation of the unit 2, the heat exchanger 13, and the cooling tower 1, as shown by the thick solid line flow path E in the figure.
The cooling water is forcibly circulated by a pump 17 in the order of 4 and heated by heat absorption in the unit 2 and heat absorption in the heat exchanger 13, and is cooled by heat radiation in the cooling tower 14.

Note that the direction of the white arrow in the figure indicates the direction of heat movement at each heat exchange site.

() Heating operation mode (see Figure 3) Water as a heat medium fluid for heating is used to dissipate heat from the main heat exchanger 9 of the heat pump 1 and the cold/hot water unit 2, as shown by the thick solid line flow path F in the figure. Exchange part 2
c, the heat exchanger 13 and the indoor heat exchanger 3 are forcibly circulated in this order by the pump 4, and heated to a predetermined temperature by the main heat exchanger 9, the heat exchange section 2c, and the heat exchanger 13, and the room is heated by the hot water. It will be done.

The refrigerant of the heat pump 1 is circulated in the order of the main heat exchanger 9 as a condenser, the expander 7, and the air heat exchanger 8 as an evaporator, as shown by the thick solid line flow path G in the figure. The heat exchanger 9 radiates heat to the heating circulating water, and the air heat exchanger 8 absorbs heat from the outside air.

Note that by diverting the refrigerant that has exited the main heat exchanger 9 to the auxiliary heat exchanger 10 serving as an evaporator, as shown by the thick solid line flow path G' in the figure, the water sent by the auxiliary pump 15 can be reduced. Cold water can be extracted from the flow path C by absorbing heat from the flow path C.

In addition, the cooling water of the engine 5 is circulated in the same flow path D as in the cooling operation mode, and the heat absorbed by the engine 5 and the exhaust gas heat exchanger 11 is exchanged with the endothermic heat exchange section 2b of the cold/hot water unit 2. It is released in section 13. In this case, the cooling water circulation pump 17
stops.

The above is the flow of each heat medium fluid in the cooling operation mode and the heating operation mode.
The system's automatic operation control for the required load will be explained below. In this case, the speed regulating mechanism 12 of the engine 5 operates based on a control signal issued from the control circuit 18 based on the detection result of the temperature sensor S ₁ that detects the temperature of the fluid supplied to the indoor heat exchanger 3.
In addition to being automatically controlled, the capacity of the compressor 6 is controlled based on the detection result of a temperature sensor _S2 that detects the inlet temperature of the main heat exchanger 9, and furthermore, the on/off and output control of the chilled/hot water unit 2 is controlled. , based on the detection of the temperature of the cold water taken out from it [detected by the temperature sensor _S2 ] or the temperature of hot water [detected by the temperature sensor _S1 ].

Incidentally, FIG. 4 shows the performance characteristics in the operation control of this system.

When air conditioning operation starts, first heat pump 1
is started and the engine 5 is first operated at a predetermined low rotation speed (for example, 750 rpm). When the load on the air conditioning side increases and the temperature detected by temperature sensor S ₂ changes (temperature increases during cooling, temperature decreases during heating), the fourth
As shown as a capacity control region in the figure, the compressor 6 is controlled to increase its capacity from 2-cylinder operation to 4-cylinder operation, 6-cylinder operation, and 8-cylinder operation in sequence. When the required load further increases and the temperature detected by the temperature sensor _S1 deviates from the set value, the speed regulating mechanism 12 operates to increase the engine speed to a predetermined high speed, as shown in the rotation control range in FIG. (for example
1500rpm). In this way, the temperature of the water supplied to the indoor heat exchanger 3 is maintained at a set value (for example, 7° C. during cooling and 45° C. during heating) by compressor capacity control and engine speed control.

When the engine speed reaches a predetermined high speed (1500 rpm), the capacity of the heat pump 1 reaches its upper limit, and when the required load increases further, this is detected by the temperature sensor _S2 , and the control circuit 18 issues a start command to the chilled/hot water unit 2. It is brought out and ignited.

In this case, the standby time is short because the unit 2 receives engine exhaust heat in advance from the endothermic heat exchange section 2b. Since the minimum capacity of the cold/hot water unit 2 is approximately 30% of the maximum capacity, the temperature of the circulating water to the indoor heat exchanger 3 deviates from the set value (below 7°C during cooling, and below 7°C during heating).
(changes to 45℃ or higher). This is detected by temperature sensor _S1 , and the engine speed is controlled to reduce, and the system stabilizes when the required load and overall system capacity are balanced.

When the required load further increases, the temperature detected by the temperature sensor _S1 changes (increases during cooling, decreases during heating), and the engine speed rises to a predetermined high speed (1500 rpm) to correspond to the load. When the required load further increases, the temperature on the outlet side of the cold/hot water unit 2 changes, and the temperature sensor S ₂ detects a temperature rise during cooling, and the temperature sensor S ₁ detects a temperature drop during heating. The capacity increase control of the cold/hot water unit 2 is performed according to the temperature change as shown in the load control range of .

Further, when the required load decreases, the capacity of the chilled/hot water unit 2 is controlled to decrease accordingly, and is lowered to the minimum capacity. When the required load further decreased, the temperature sensor S ₁ deviated from the set temperature (dropped below 7℃ during cooling and rose above 45℃ during heating).
is detected, the engine speed is controlled to decrease from high speed (1500rpm), and heat pump 1
capacity decreases until it balances with the load. When the load further decreases, the temperature sensor S ₁ detects a decrease in unit outlet temperature during cooling, and the temperature sensor S ₁ detects an increase in unit outlet temperature during heating, and a command to stop operation of the cold/hot water unit 2 is issued.

When cold/hot water unit 2 stops, temperature sensor S ₁
However, it senses a temperature rise during cooling and a temperature drop during heating, and based on this, the engine speed is increased to a high speed (1500 rpm), the capacity of heat pump 1 is increased to 100%, and chilled/hot water unit 2 is
This will compensate for the 30% reduction in capacity due to the suspension of operations. As a result, when the required load decreases, _the engine speed changes within the control range (1500~
750rpm) is controlled to reduce the load. When the load decreases further after reaching a low rotational speed (750 rpm), the inlet temperature of the main heat exchanger 9 changes (decreases during cooling, increases during heating), and this is detected by temperature sensor S ₂ and the compressor 6 is activated. When the cylinder reduction control is performed and the temperature sensor S ₁ detects a temperature below a set temperature (for example, 5° C.), a command to stop the engine 5 is issued and the heat pump 1 is stopped.

[Another example]

The above example shows the case of an air conditioning system, but
It can be applied to a hot water supply system or a hot water supply and heating system. Further, in the case of this hot water supply system or hot water supply/heating system, a gas burner or an oil burner can be used as the combustion type auxiliary heat source device 2.

[Brief explanation of drawings]

The drawings show an embodiment of the method for controlling the operation of an engine heat pump system according to the present invention, in which Fig. 1 is a block diagram of the entire system, Fig. 2 is a flow diagram of the cooling operation mode, and Fig. 3 is a flow diagram of the heating operation mode. FIG. 4 is a performance characteristic diagram, and FIG. 5 is a performance characteristic diagram in the conventional operation control method. 1...Engine heat pump, 2...Combustion type auxiliary heat source device, 5...Engine, _S1 ...Temperature sensor.

Claims (1)

[Claims] 1. An engine heat pump 1 and a combustion type auxiliary heat source device 2 are arranged in series in a heat transfer fluid circulation path, and only the engine heat pump 1 is operated in a low load region, and at the same time when the required load is The capacity of the engine heat pump 1 is increased or decreased by controlling the engine speed corresponding to the increase or decrease, and in high load areas exceeding the engine heat pump capacity, the engine heat pump 1 and the auxiliary heat source device 2 are operated in parallel, and the auxiliary heat source device is activated according to the required load. 2. A method for controlling the operation of an engine heat pump system that controls the capacity of
The rotation speed of the engine 5 is controlled based on the detection result of the temperature sensor S ₁ to maintain the temperature of the heat medium fluid supplied to the load side at the set value, and the capacity is gradually increased as the auxiliary heat source device 2 is started. An operation control method for an engine heat pump system that controls the engine speed to decrease. 2. The operation according to claim 1, wherein the engine heat pump 1 is driven by a gas engine 5, and the combustion type auxiliary heat source device 2 is a gas direct-fired absorption type cold/hot water unit. Control method.