JPS5919257B2 - How to control the flow rate of a water cooler/heater pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cold/hot water pump for a cold/hot water machine and a method for controlling the flow rate of a cooling water pump.

The cooling operation of the gas absorption type water chiller/heater according to the embodiment will be described below.

Conventionally, when using a gas absorption type water chiller/heater for cooling, a constant amount of chilled water and cooling water was circulated regardless of the cooling load in order to compensate for flow rate fluctuations within the water chiller/heater.

Sudden fluctuations in cold water cause freezing in the evaporator, and sudden fluctuations in cooling water cause a temperature rise in the condenser, making stable operation impossible. Nothing other than water flow rate control was performed. To this end, conventionally, as an improvement measure, a bypass valve T was provided between the outgoing header 6 and the return header 8 for the cold water line as shown in FIG.
A system was adopted in which a constant amount of water could be circulated regardless of the load, and the flow rate to the cold/hot water machine 1 was kept constant. Regarding the cooling water line, the temperature was adjusted by turning on and off the cooling tower fan 3 using a cooling water temperature regulating thermostat 11 to keep the flow rate to the water chiller/heater 1 constant. However, in this method, the cold water pump 5 and the cooling water pump 4
is being driven.

It is well known that generally air conditioning water coolers and hot water machines are rarely operated at high loads and are often operated at intermediate load ranges. In other words, if we consider the conventional method for water chiller/heater operation with many intermediate load ranges, it is uneconomical as it wastes a lot of power. A conventional method for controlling the flow rate of cold and hot water in consideration of this point is a method using a calorimeter. This measures the flow rate of hot and cold water flowing into the water cooler and hot water machine and the temperature difference between the inlet and outlet, calculates the product, calculates the amount of heat, and controls the flow rate. That is, it required complicated measurement and control such as flow rate measurement and calculation. The present invention has been made in view of this point, and uses a simple detection system and control system based on the temperature difference at the entrance and exit of the water cooler and the signal indicating the number of operating cold/hot water pumps, without using a calorimeter. It controls the flow rate and reduces the power consumption of the pump, contributing to energy conservation. The present invention will be explained in the case of cooling operation based on the drawings.

Fig. 2 is a system diagram of an air-conditioning water cooler/heater related to the flow rate control method for a water chiller/heater pump according to the present invention, and Fig. 3 is a control circuit diagram of a gas absorption type water chiller/heater pump embodying the present invention. be.

The example shown in FIG. 3 is a case where there are two cold/hot water pumps and two cooling water pumps. Relay R1 is energized when the power is turned on when the cold/hot water machine starts operating, and the cold water pump 5 and the cooling water pump 4 are activated.
is driven. R2 is a relay for stopping the operation of the cold water pump 5'' and the cooling water pump 4'. In this case, the fact that R2 is not energized means that the cold water pump 55 and the cooling water pump 4 are stopped.
' is being operated, and R2 is not excited immediately after the start of operation of the water chiller/heater. (If there are two chilled water pumps and two chilled water pumps, this indicates that the number of operating chilled water pumps is two.) Continue cooling operation until the temperature difference between the input and output of the chiller/heater becomes 25°C or less. If the contact T2 becomes 0n and becomes 0n when the cold water temperature from the water cooler/heater is 7.5°C, for example, the contact t becomes 0n and becomes 0n when the gas input is 1/2 or less.If the contact K2 becomes 0n, the timer is activated. T2 is activated, and after a certain period of time, relay R2 becomes ON, and cold water pump 5'' and cooling water pump 4'' are stopped.
In other words, even without measuring the flow rate, the calorie of the chilled water system is roughly calculated and controlled using the flow rate determined by the number of operating pumps and the temperature difference signal at the inlet and outlet of the water cooler/heater.
Here, K2 and t are for backing up the signal T2, which is the difference in temperature between the cold water in and out of the water cooler/heater. The symbol K3 is a contact for anti-freezing, which operates when the cold water or refrigerant temperature falls below the set temperature. Next, the conditions for operating two pumps from one pump in operation are 0n, relay R2 indicating one pump operation is 0n, and the cold water temperature difference at the outlet and outlet of the water chiller/heater body is 0n, for example, 5°C or more. When the contact t1 becomes 0n, the timer T1 starts operating, and after a certain period of time, the contact T1 is turned 0ff, R2 is turned 0ff, and the second cold water pump 5' and cooling water pump 4' are started to operate the two units. Become.
K1 is a contact point that operates at a gas input of 1/2 or more, and is also used as a backup. With the control circuit as described above, the flow rate of cooling water can be controlled in accordance with the load of the water chiller/heater. Even when three or more chilled water pumps or cooling water pumps are installed, the same purpose can be achieved by using a signal based on the number of pumps in operation and a signal indicating the temperature difference between the chilled water in and out of the water cooler/heater, which is set appropriately.

Let us consider the effect of a hot and cold water machine that implements the method for controlling the flow rate of chilled water and cooling water according to the present invention when there are two chilled water pumps and two chilled water pumps. It is well known that the operating load of a water cooler/heater for air conditioning is usually carried out in an intermediate load range.For example, if the cooling time during the cooling season is 1000 hours, the operating time when the water cooler/heater load is 50% or less is 50%. If so, the operating time of the auxiliary equipment would be 750 hours, and the power consumption of the auxiliary equipment would be reduced by 25% compared to the conventional system, resulting in a large energy-saving effect. The above describes the cooling operation of a gas absorption type water chiller/heater, but for heating operation, it is necessary to set the hot water temperature difference between the input and output of the chiller/heater and the hot water temperature at the outlet of the chiller/heater to appropriate values for heating operation. good. Of course, in this case, the operation of the cooling water pump is still stopped. Although the embodiments have been described above in which the present invention is applied to a gas absorption type water chiller/heater, the present invention can also be applied to, for example, cooling by a turbo chiller. Even in such a case, the power consumption of the cold water pump and the cooling water pump can be reduced by using a simple detection system and control system.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a conventional water cooler/heater, FIG. 2 is a system diagram of an air conditioning water cooler/heater related to the method of controlling the flow rate of a pump for a water cooler/heater according to the present invention, and FIG. It is a control circuit diagram of the implemented gas absorption type water chiller/heater pump. 1... Cold/hot water machine, 2... Cooling tower, 3.
...Cooling tower fan, 4,4//-...Cooling water pump, 5,52...Cold/hot water pump, 6...
... Header, 7... Bypass valve, 8.
...Return header, 9...Two-way valve, 10.
... Air conditioning terminal, 11 ... Cooling water thermostat.

Claims (1)

[Claims] 1 In a cold/hot water machine, a plurality of cold/hot water pumps and a plurality of cooling water pumps are provided, and the cold/hot water pumps and the cooling water pumps are connected in parallel to the cold/hot water circuit and the cooling water circuit, respectively, and the number of operating cold/hot water pumps is indicated. A method for controlling the flow rate of a cold/hot water pump, characterized in that the cold/hot water pump and the second or subsequent cooling water pumps are started and stopped based on a signal and a temperature difference between the cold and hot water at the entrance and exit of the main body of the cold/hot water machine.