Institute of Avionics and Aeronautics (Department of Mechanical & Aerospace Engineering)

ME-437 ; Refr. & Aircond. Class : F-10 Sec. A&BMarks : 100 Time : 2 weeks

Name : _____________________Reg No : _____________________Date : 01 October 2013

Design Assignment

A food storage locker requires a refrigeration capacity of 15 ton; (52.755 KW). Its suggested refrigerant is Ammonia and works between a condenser temperature of 35 C and evaporator temperature of -5 C. The maximum Ammonia flow rate is to be restricted to maximum value of 0.04 kg/s to take care of all available components operating limits. The available compressor in market has maximum isentropic efficiency of 80%.

You are to design and suggest a workable refrigeration cycle and also give the design of compressor in term of RPM, bore & dia.

Also calculate and optimize the electricity charges required to operate the system. Assume 80% of the total cycle power required (Condenser, evaporator & compressor) is consumed by compressor; so you need to optimize the compressor performance.

NOTE: You are required to make a preliminary design to achieve the desire cooling capacity of 15 tons by establishing the states; 1, 2, 2s, 3 and 4 ( using appropriate wet, superheated and wet regions while keeping the TH and TL as 35 C and -5 C respectively). Neglect the pressure losses in all components. Starting with maximum permissible mass flow rate, calculate the power of compressor, which will give you total KW load of cycle. Finally, you can see and suggest, how to reduce the electricity consumption