Energy Optimization Under Part Load Of Screw Water-cooled Chiller

Chiller air conditioning systems as a major source of cold, widely be produced and used, its energy efficiency seriously affect the energy level of the building. Optimization and simulation of chiller energy performance in most conditions year-round has been to set up the relationship with the external parameters, and was short of discussion of the impact of their own arguments. Therefore, this article is in the case of keeping external parameters constant. The internal of refrigerant cycle unit is changed to improve efficiency of the evaporated and refrigerant cycle performance.Firstly, I have preliminary experimental measurements on the experimental chiller. It found that when the compressor is under low load conditions, the higher the temperature of the chilled water, the operation of chiller more favorable. The water speed has less affected on the chiller. Then analysis of the measured parameters by thermodynamic and found that in the thermodynamic process of the refrigerant cycle, the loss of exergy in the evaporator is the largest, it occupies more than 60% the exergy loss in the refrigeration cycle. According to this measurement, determined that improvping the evaporator heat transfer performance and having targeted water system parameters were set as experimental programs.This experiment increase a bypass pipe from the condenser to the evaporator in the original chiller to have a realization of the improvement of the evaporator heat transfer performance in partial load. The bypass line is made up of 4 different routes bypass pipe diameter and three different access methods. Set water system parameters that chilled water outlet temperature is 10℃, flow rate of 22.3m~3/h; cooling water inlet temperature is 30℃, flow rate of 32m~3/h.After a number of experiments, this paper found that: adjusting the valves on the bypass pipeline can regulate the performance of the unit, for example when the pipe diameter of bypass line was φ28n, the valve opening 40 ° is beneficial for the unit most. But when the valve fully open fully, the compressor will have the fluid refrigerant. Different bypass diameters have different impact on plant performance. when using a large diameter bypass, chiller’s performance is the most sensitive for valve opening degree. The most favorable diameter of bypass pipe is φ16 diameter, it is not necessary to adjust the valve. the chiller can maintain a more high performance yet. When the diameter of bypass pipe is φ28 and φ22, the cooling capacity of chiller had a small rise in the valve opened appropriately and the exhaust temperature and exhaust pressure decreased. When the bypass line link the main circulating pipe vertical and inclined, the chiller had a better performance. Based on the second law of thermodynamics, the exergy loss of evaporator reduced greatly after chiller’s bypass reconstruction, exergy efficiency had improved significantly, and the thermodynamic perfectibility of the chiller also had a certain improvement.