A working fluid in a closed loop undergoes the following cycle: • 1-2 Isentropic compression • 2-3 Isobaric heat addition • 3-4 Isentropic expansion • 4-1 Isobaric heat rejection Identify the temperature-entropy (T-s) diagram that illustrates this cycle. T 2 2 3 3 4 S 1 4 4 2 3 3 4 S

A refrigerator operates according to a Brayton cycle, diagrammed below. The gas conditions (gamma=1.4) at point 1 are P1,V1 and T1=100K. It is known that V1 =10V2=5V3=V4/2.Consider that Tf is the temperature of the cold source and Tq is the temperature of the hot source. It is known that Tq and Tf are, respectively, the maximum and minimum possible for the refrigerator to operate under these conditions. reservoirs would have a coefficient of performance closer to:

Air within a piston-cylinder assembly executes a Carnot heat pump cycle, as shown in the figure below. For the cycle, TH = 600 K and Tc = 300 K. The energy rejected by heat transfer at 600 K has a magnitude of 1000 kJ per kg of air. The pressure at the start of the isothermal expansion is 325 kPa. p-v diagram for a Carnot gas refrigeration or heat pump cycle. Assuming the ideal gas model for the air, determine: (a) the magnitude of the net work input, in kJ per kg of air, and (b) the pressure at the end of the isothermal expansion, in kPa.

In an absorption refrigerator, the energy driving the process is sllPplied not as work, but as heat from a gas flame. (Such refrigerators commonly use propane as fuel, and are used in locations where electricity is unavailable. *) Let us define the following symbols, all taken to be positive by definition:                     Qf = heat input from flame                      Qe = heat extracted from inside refrigerator                      Qr = waste heat expelled to room                      Tf = temperature of flame                                         Te temperature inside refrigerator                                           Tr = room temperature Explain why the "coefficient of performance" (COP) for an absorption refrigerator should be defined as Qc/Qf.

In an absorption refrigerator, the energy driving the process is sllPplied not as work, but as heat from a gas flame. (Such refrigerators commonly use propane as fuel, and are used in locations where electricity is unavailable. *) Let us define the following symbols, all taken to be positive by definition:                     Qf = heat input from flame                      Qe = heat extracted from inside refrigerator                      Qr = waste heat expelled to room                      Tf = temperature of flame                                         Te temperature inside refrigerator                                           Tr = room temperature Use the second law of thermodynamics to derive an upper limit on the COP, in terms of the temperatures Tf, Te, and Tr alone.

Q: The working fluid, in a steady flow process flows at a rate of 220 kg/min. The fluid rejects 100 kJ/s passing through the system. The conditions of the fluid at inlet and outlet are given as : C1 = 320 m/s, p1 = 6.0 bar, u1 = 2000 kJ/kg, v1 = 0.36 m3/kg and C2 = 140 m/s, p2 1.2 bar, u2 = 1400 kJ/kg, v2 = 1.3 m3/kg. The suffix 1 indicates the condition at inlet and 2 indicates at outlet of the system. Determine the power capacity of the system in MW. The change in potential energy may be neglected. Fluid Fluid leaves System enters

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The manufacturer of the device claims that it accepts a heat transfer at a rate of QH = 3.0 kW from a low-grade source of geothermal heat at TH = 80ºC and rejects heat at rate QC to the atmosphere at TC = 20ºC. The device operates at steady state and produced work at a rate of W= 2.5 kW. There are no other heat or work transfers from the device. a.) What is the rate at which the device rejects heat to the atmosphere, QC ? b.) Is this device possible? Justify your answer using an entropy balance.

Air within a piston-cylinder assembly executes a Carnot heat pump cycle, as shown in the figure below. For the cycle, TH = 400 K and Tc = 300 K. The energy rejected by heat transfer at 400 K has a magnitude of 625 kJ per kg of air. The pressure at the start of the isothermal expansion is 325 kPa. TH Te p-v diagram for a Carnot gas refrigeration or heat pump cycle. Assuming the ideal gas model for the air, determine: (a) the magnitude of the net work input, in kJ per kg of air, and (b) the pressure at the end of the isothermal expansion, in kPa.

Q1: An engineer claimed that his device produces two streams of 1 am air (outlet 1) and 1.5 atm (outlet 2) at temperatures of 460 °R and 635 °R, respectively, if he enters 530 °R of the air at 5.1 atm. If the ratio of outlet 2 to outlet 1 is 0.6, justify the engineer's claim. Assume ideal gas process with a constant heat capacity of 0.24 Btu/lb.°R.