Figure P10.30 shows a two-stage vapor-compression refrigeration system with ammonia as the working fluid. The system uses a direct-contact heat exchanger to achieve intercooling. The evaporator has a refrigerating capacity of 30 tons and produces 2208F saturated vapor at its exit. In the first compressor stage, the refrigerant is compressed adiabatically to 80 lbf/in.2 , which is the pressure in the direct contact heat exchanger. Saturated vapor at 80 lbf/in.2 enters the second compressor stage and is compressed adiabatically to 250 lbf/in.2 Each compressor stage has an isentropic efficiency of 85%. There are no significant pressure drops as the refrigerant passes through the heat exchangers. Saturated liquid enters each expansion valve. Determine (a) the ratio of mass flow rates, m # 3/m # 1. (b) the power input to each compressor stage, in horsepower. (c) the coefficient of performance.(d) Plot each of the quantities calculated in parts (a)(c)versus the direct-contact heat exchanger pressure rangingfrom 20 to 200 lbf/in.2 Discuss.
Week 4: Film continued & Lecture Laborers were only paid $1/day for working from dawn to dusk 1920s-1930s: over 100,000 Filipinos immigrated to the US o the imagination of the laborers was that the USA was all about wealth – ironically, they arrived during the Great Depression lived in camps kids worked 10 hours/day and made 8cents/hour didn’t have food to eat so ate animals like frogs or crows verbal abuse – “Monkey, go home. Go where you belong” California law – A Filipino cannot marry a White Weekends – when they got paid, they went dancing Rooster fighting Very low ratio of men to women (16:1 or 32:1) Life got better for the Filipinos around the 1970s-1980s o Some went back to their native
