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This post was last edited by Zhang Xinlin from Binglun Environment on December 22, 2019, at 14:52. [Daily Question] is divided into three sections: fundamentals of refrigeration, selection criteria for refrigeration equipment, and maintenance of refrigeration equipment. [Reward Rules] Those who comment on this post will receive 1–3 wealth points; those who provide accurate answers will get 10–15 points. The rewards are valid for two days, and the answers will be announced after that period. Fundamentals of Refrigeration section – Pressure-enthalpy diagrams – Refrigeration calculations (2) I. Overview In refrigeration calculations, pressure-enthalpy diagrams are used; for example, when selecting a throttle valve, it is necessary to know the flow rate of the refrigerant, and when choosing an evaporative cooler, it is necessary to know the heat rejection capacity, among other things. Here are several basic terms used in pressure-enthalpy diagram calculations: 1. Cooling capacity per unit mass, KJ/KG; 2. Cooling capacity per unit volume, KJ/m3; 3. Mass flow rate of the refrigerant, KG/h; 4. Volume flow rate of the refrigerant, m3/h; 5. Condensation heat load per unit mass, KJ/KG; 6. Theoretical compression work per unit mass, KJ/KG; 7. Coefficient of Performance, COP. These 7 parameters will be discussed in the daily questions to follow when it comes to cooling calculations. Question 1: Please refer to the figure below. Use H1, H2, H3, and H4 to express the unit condensation heat load (KJ/KG). (Hint: Use the enthalpy difference.) Answer: H2 – H3 ============================== Premium promotion: Daily questions on rotating equipment – refrigeration applications; their value and functions: https://bbs.hcbbs.com/thread-2848974-1-1.html. Internal training materials for manufacturers of screw refrigeration compressors related to rotating equipment: https://bbs.hcbbs.com/thread-2850090-1-1.html