| Summary: | 碩士 === 國立勤益科技大學 === 冷凍空調系 === 103 === To carry out data tests on screw type two-stage compressor high temperature heat pump system with flash tank. Modify the prototype system consist of plate heat exchanger, direct-expansion watercooler and shell & tube type oil cooler to new system with flash tank, flooded-type ice watercooler and four-tube shell & tube type water cooler, then analyse the performance of both systems under different water temperature, followed by carry out performance test on the new system under different conditions to figure out effects of different air pressure and condensing temperature in flash tank to the system’s performance and to obtain the optimum air pressure of the flash tank. Results shown that the new system has an increase of 23% in average performance which proved that the new system is more efficient than prototype system, and the optimum air pressure is obtained by increase the intermediate temperature obtained from formula by 26%.
This research also improved system’s heating efficiency and performance by collect the waste heat from cooling water in cooling water collector of four-tube shell & tube type oil cooler and transfer to condenser inlet to preheat the cooling water . Experimental results shown that system with this method has an improved performance of 12% and 35% at condensing temperature of 45°C and 85°C respectively. This proved the importance of recovery of waste heat of cooling water of oil cooler as this method able to improve system’s performance at every condensing temperature.
This research also developed a mini-sized high pressure air system for heat pump system with single-stage compressor to study the effect of flask tanks’ ability of vapor injection to system’s performance by carry out performance test with four different electronic expansion valve with different environmental temperature and constant water temperature of 16°C. Experimental results shown that control on heat pump’s system’s vapor injection able to improve overall performance of system, such that precise control on flask tank’s vapor injection could miminize the wastage of performance significantly compraed to system without control on vapor injection.
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