Exercícios de Termodinâmica II - Modificações em Ciclos de Refrigeração

Lista 3 Disciplina Termodinâmica II Prof Gustavo Rodrigues de Souza 1033 An ideal vaporcompression refrigeration cycle is modified to include a counterflow heat exchanger as shown in Fig P1033 Ammonia leaves the evaporator as saturated vapor at 10 bar and is heated at constant pressure to 5C before entering the compressor Following isentropic compression to 18 bar the refrigerant passes through the condenser exiting at 40C 18 bar The liquid then passes through the heat exchanger entering the expansion valve at 18 bar If the mass flow rate of refrigerant is 12 kgmin determine a the refrigeration capacity in tons of refrigeration b the compressor power input in kW c the coefficient of performance Discuss possible advantages and disadvantages of this arrangement 126 Natural gas at 23C 1 bar enters a furnace with the following molar analysis 40 propane C3H8 40 ethane C2H6 20 methane CH4 Determine a the analysis in terms of mass fractions b the partial pressure of each component in bar c the mass flow rate in kgs for a volumetric flow rate of 20 m³s 1281 An air conditioner operating at steady state takes in moist air at 28C 1 bar and 70 relative humidity The moist air first passes over a cooling coil in the dehumidifier unit and some water vapor is condensed The rate of heat transfer between the moist air and the cooling coil is 11 tons Saturated moist air and condensate streams exit the dehumidifier unit at the same temperature The moist air then passes through a heating unit exiting at 24C 1 bar and 40 relative humidity Neglecting kinetic and potential energy effects determine a the temperature of the moist air exiting the dehumidifier unit in C b the volumetric flow rate of the air entering the air conditioner in m³min c the rate water is condensed in kgmin d the rate of heat transfer to the air passing through the heating unit in kW Exercícios 1029 respostas a 661 kW b 261 1032 respostas a evaporador 1 4823 kgmin evaporador 2 2943 kgmin b 5329 kW c 2291 kW 1033 respostas a 6324 TR b 1085 kW c 205 126 respostas a C3H8 05365 C2H6 03659 CH4 00976 b C3H8 04 bar C2H6 04 bar CH4 02 bar c 267 kgs 1213 respostas 992 kJkg 2534 kJ 1281 respostas a 96 oC b 4863 m3min c 0515 kgmin d 804 kW 12103 respostas a 113385 kgs b 2908 kgs 1346 respostas 1152x106 kW e 15085x106 kW 1348 resposta 27838 m3h 1350 resposta 0102 kgs e 1363 respostas a 47483 kJkg b 26803 kJkg c 46359 kJkg d 44429 kJkg Além disso estude e faça exercícios sobre os temas presentes nos slides