problem 1: i. Check the applicability of the ideal gas modal for Refrigerant 134
ID: 2115226 • Letter: P
Question
problem 1:i. Check the applicability of the ideal gas modal for Refrigerant 134a at a temperature of 80C and a pressure of 1.6 Mpa.
ii. In what kind of pot will a given volume of water boil at a higher temperature: a tall and narrow one or a short and wide one? Explain.
iii. Saturated liquid water contained in a closed, rigid tank is cooled to a final state where the temperature is 50 degrees C and the masses of saturated vapor and liquid present are 0.03 and 1999.97 kg respectively. Determine the heat transfer for the process in kJ.
Problem 2:
Carbon dioxide, (CO2) gas, initially at 70 degrees F, 15 lbf/in2, and 1ft3, is compressed in a piston-cylinder assembly. During the process, the pressure and specific volume are related by pv1.2=constant. The amount of energy transfer to the gas by work is 45 Btu/lb of CO2. Determine the final temperature and the heat transfer in Btu/lb of gas.
Problem 3:
A cycle, composed of three processes: polytropic compression (n=1.5) from 137 kPa and 38 degrees C to state 2, constant pressure from state 2 to state 3, and constant volume from state 3 to state 1. The heat rejected is 1560 kJ/kg, and the substance is air. Determine:
a. The pressures, the temperatures, and specific volumes around the cycle
b. the heat added
c. the work for each process and the net work.
Problem 4:
A nitrogen line, 300 K and 0.5 Mpa, shown in the figure, is connected to a turbine that exhausts to a closed initially empty tank of 50m3. The turbine operates to a tank pressure of 0.5 Mpa, at which point the temperature is 250K. Assuming the entire process is adiabatic, determine the turbine work.
Problem 5:
i. An inventor claims to have developed a refrigeration system that removes heat from cooled region at -85C and transfers it to the surrounding air at 25C while maintaining a COP of 5.5. Is this claim reasonable? Why?
ii. In a steam power plant, 6000kg/s of steam enters the turbine at 8MPa, 480C, and expands to 0.7 Mpa. If the turbine has an efficiency of 90%, calculate the turbine net work in kW, the actual turbine exit temperature and entropy.
Problem 6:
i. It is desired to double the efficiency or a Carnot heat engine from 30% by raising its temperature of heat addition, while keeping the temperature of heat rejection constant. What percent increase in high temperature is required?
ii. A Carnot cycle engine using 1 kg air has the following conditions: heat addition beginning at 15 MPa and 1200 K and continuing until the pressure is 10 MPa; isothermal compression from 100kPa and 300 K and continuing until the pressure is 150 kPa. Determine:
a) the heat transfer into the cycle
b) the heat transfer from the cycle
c) the work for each of the processes
d) the cycle efficiency problem 1:
i. Check the applicability of the ideal gas modal for Refrigerant 134a at a temperature of 80C and a pressure of 1.6 Mpa.
ii. In what kind of pot will a given volume of water boil at a higher temperature: a tall and narrow one or a short and wide one? Explain.
iii. Saturated liquid water contained in a closed, rigid tank is cooled to a final state where the temperature is 50 degrees C and the masses of saturated vapor and liquid present are 0.03 and 1999.97 kg respectively. Determine the heat transfer for the process in kJ.
Problem 2:
Carbon dioxide, (CO2) gas, initially at 70 degrees F, 15 lbf/in2, and 1ft3, is compressed in a piston-cylinder assembly. During the process, the pressure and specific volume are related by pv1.2=constant. The amount of energy transfer to the gas by work is 45 Btu/lb of CO2. Determine the final temperature and the heat transfer in Btu/lb of gas.
Problem 3:
A cycle, composed of three processes: polytropic compression (n=1.5) from 137 kPa and 38 degrees C to state 2, constant pressure from state 2 to state 3, and constant volume from state 3 to state 1. The heat rejected is 1560 kJ/kg, and the substance is air. Determine:
a. The pressures, the temperatures, and specific volumes around the cycle
b. the heat added
c. the work for each process and the net work.
Problem 4:
A nitrogen line, 300 K and 0.5 Mpa, shown in the figure, is connected to a turbine that exhausts to a closed initially empty tank of 50m3. The turbine operates to a tank pressure of 0.5 Mpa, at which point the temperature is 250K. Assuming the entire process is adiabatic, determine the turbine work.
Problem 5:
i. An inventor claims to have developed a refrigeration system that removes heat from cooled region at -85C and transfers it to the surrounding air at 25C while maintaining a COP of 5.5. Is this claim reasonable? Why?
ii. In a steam power plant, 6000kg/s of steam enters the turbine at 8MPa, 480C, and expands to 0.7 Mpa. If the turbine has an efficiency of 90%, calculate the turbine net work in kW, the actual turbine exit temperature and entropy.
Problem 6:
i. It is desired to double the efficiency or a Carnot heat engine from 30% by raising its temperature of heat addition, while keeping the temperature of heat rejection constant. What percent increase in high temperature is required?
ii. A Carnot cycle engine using 1 kg air has the following conditions: heat addition beginning at 15 MPa and 1200 K and continuing until the pressure is 10 MPa; isothermal compression from 100kPa and 300 K and continuing until the pressure is 150 kPa. Determine:
a) the heat transfer into the cycle
b) the heat transfer from the cycle
c) the work for each of the processes
d) the cycle efficiency
Explanation / Answer
can you mention the initial temperature of the refrigerant. It is not clear in the question ."80C"= this is written
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