application
High Efficiency Air Conditioning System Energy Saving Solution
High Efficiency Air Conditioning System Energy Saving Solution
The equipment that consumes the most power in the air conditioning chiller system is the water-side system (including chiller, chilled water pump, cooling water pump, and cooling water tower). Generally, the power consumption of the water-side system accounts for about 50% to 60% of total electricity consumption of air conditioning system, and the performance of the central air-conditioning system is controlled by the mutual cooperation of chiller, water pumps, cooling water towers. The load of the air-conditioning system is not fixed. The cooling demand of the building will vary from 25 to 100% due to different climates, sunshine and the amount of internal heat sources. In the past, the control method of traditional air conditioning system drived the compressor, water pump and fan at a fixed speed and could not adjust the cooling capacity in response to the change of heat load, resulting in a lot of energy waste. Therefore, the frequency control has become an indispensable key technology in today's air conditioning system.
1. Chilled Water Pump Inverter Control
When the air conditioning cooling load required by the building is low, part of the two-way valve will close or reduce the opening to reduce the amount of chilled water entering the chilled water fan coil. The differential pressure sensor will detect the pressure difference caused by part of the two-way valves being closed or reduced opening and send signals back to the inverter to control the chilled water pump speed. In such a system, due to the reduction of the load of the air conditioner, the lower water flow in the chilled water main pipe and the lower water flow resistance are controlled, and the energy saving effect of the chilled water pump is obtained.
The differential pressure measurement point should be located at the farthest end of the heat exchanger or the place where the maximum differential pressure of the heat exchanger is required. The closer the differential pressure measurement point is to the pump, the smaller the adjustable range of the pump and the lower the energy saving benefit.
2. EnergySaving Control of Cooling Water Tower Fan
Generally, each 1°C reduction in cooling water inlet temperature can reduce the power consumption of the chiller by 1.5~2.0%. However, the external wet bulb temperature will affect the minimum water temperature capacity of the cooling water tower. Under the limit of the external wet bulb temperature, over-high fan speed cannot effectively reduce the cooling water temperature, but increase the fan energy consumption, resulting in poor energy efficiency.
We adjust and control target temperature according to the external wet bulb temperature, and the cooling water temperature in the tower to the inverter is fed back to the inverter. PID control lowers the cooling water tower fan speed. According to the similar law, the fan power consumption of the water tower will also be reduced by the third power of the speed reduction, so as to achieve the purpose of energy saving.
3. EnergySaving Control of Cooling Water Pump
The temperature difference between the cooling water outlet and the return water of the chiller is used to control the cooling water pump to achieve the purpose of speed reduction and energy saving.
If the temperature difference is large, the speed of the cooling water pump should be increased to increase the circulation speed of the cooling water. If the temperature difference is small, the speed of the cooling water pump can be reduced to slow down the circulation speed of the cooling water.
Example of Energy-Saving Improvement of Air Conditioning in Rhymebus Third Factory
The project is to improve the water side system of air conditioners in Rhymebus Third Factory, before and after the hardware (pipeline lift loss) and software (chilled water/cooled water circulation control logic), the project has:
1. Pipeline Lift Loss Improvement
Traditional ice water pipeline will be equipped with check valve to stop the ice water from flowing back to the ice water host which is not turned on. But the check valve often causes a small loss of lift, and it is difficult to completely stop the ice water from seeping back, which causes additional loss of ice water temperature.
2. Ice Water Pump Inverter Control
The ice-water circulation is controlled by the differential pressure signal for the ice-water area pump.
Control objective: to provide the differential pressure required by the end heat load.
Control objective: to provide the differential pressure required by the end heat load.
3. Cooling Water Pump/Fan Inverter Control
A. Cooling water pump speed is controlled by temperature difference signal of outlet/return water temperature. Control objective: temperature difference 4~5°C.
B. Cooling water pump speed is controlled by temperature difference signal of atmospheric wet bulb/return water temperature. Control objective: temperature difference 2~3°C.
4. Energy Consumption Monitoring System
The energy efficiency monitoring system of ITRI is integrated with ultrasonic flow meter to calculate the precise energy consumption index of the ice and water system, so that the operation of the air conditioning system can be observed immediately and the long-term trend analysis can be made.
The annual average temperature rises, but the actual electricity consumption decreases by 24996.34 kWH, about 26.6%.
Related products
