In this thesis, the writer has designed a set of equipment, which can reduce twenty-five kilogram water per hour by way of freezing and concentrating. Besides, the writer will attach greater importance to the design and type selection of the refrigeration unit and then figure out the parameter of it.kilogram
In this process, a single stage compression refrigeration cycle going along with heat return is adopted as a way of refrigeration, and the refrigerant R134a is considered as an operating medium. Then, the sizes of evaporator and condenser, resistance of heat transfer as well as heat flux density have been calculated and checked. In addition, Copeland scroll compressors for refrigeration ZS38K4E-TFD and expanding valve TCLE-150MW are employed in this thesis. Moreover, using 3% of Na2SO4 as raw material, the writer has done an experiment of freeze concentration and analyzed the cause of refrigerant’s step phenomenon. Eventually, according to the calculated value and the result of this experiment as well as the parameters of present freeze concentration equipment in all parts, the writer has made some suggestions for improvement:
Firstly, by comparison, the writer finds out that the oil separator has a great effect on efficiency of refrigeration and suggests that oil separator should be employed to reduce the amount of lubricating oil in refrigerant in order to improve the efficiency of heat transfer.
Secondly, by comparing model parameters of compressors, the writer realizes that the compressors, which have been used so far, are far away from their best working condition. As a result, the writer proposes that the present compressors should be changed.
Thirdly, by comparing different condensers’ ability to dissipate the heat, the writer argues that the condenser employed in present is not good enough to dissipate the heat before arriving its stable working condition. Consequently, the writer advices that facilities of water spray and blow are needed to improve the condensers’ ability of dissipating the heat.
Fourthly, after comparing the operating principles of different expanding valves, the writer
suggests that the expanding valve of inner balance used in present should be replaced by that of outside balance or electronic expanding valve in order to better adapt to the changing working conditions of refrigeration.
Key words: freeze concentration, refrigeration, optimal design

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