A piston-cylinder device initially contains 2 kg of refrigerant-134a at 100 kPa and 20°C. Heat is now transferred to the refrigerant from a source at 150°C, and the piston, which is resting on a set of stops, starts moving when the pressure inside reaches 120 kPa. Heat transfer continues until the temperature reaches 80°C. Assume the surroundings to be at 25°C and 100 kPa. R-134a 100 kPa 20°C Q 150°C Problem 08.048.c - Exergy Destroyed by Piston Device with Refrigerant Determine the exergy destroyed. (You must provide an answer before moving on to the next part.) The exergy destroyed is [ kJ.

A piston-cylinder device initially contains 2 kg of refrigerant-134a at 100 kPa and 20°C. Heat is now transferred to the refrigerant from a source at 150°C, and the piston, which is resting on a set of stops, starts moving when the pressure inside reaches 120 kPa. Heat transfer continues until the temperature reaches 80°C. Assume the surroundings to be at 25°C and 100 kPa. R-134a 100 kPa 20°C Q 150°C Problem 08.048.c - Exergy Destroyed by Piston Device with Refrigerant Determine the exergy destroyed. (You must provide an answer before moving on to the next part.) The exergy destroyed is [ kJ.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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One kg of superheated steam is at 400 kPa and 400°C. Heat is added to raise the temperature to 500°C. Find the amount of heat needed (kJ) if: (a) The volume of the steam is kept constant during the heating. (b) The steam is allowed to expand during the heating (e.g., in a piston/cylinder system) such that the pressure is constant. Hint: The steam is not an ideal gas under these conditions.
A frictionless piston-cylinder device initially contains 80 L of liquid saturated with refrigerant 134a. The piston has free movement, and its mass is such that it maintains a pressure of 500 kPa on the refrigerant. The refrigerant is then heated until its temperature rises to 70 ° C. Calculate the work done during this process.
3. A mass of 2.4 kg of air at 150 kPa and 12°C is contained in a gas-tight, frictionless piston-cylinder device. The air is now compressed to a final pressure of 600 kPa. During the process, heat is transferred from the air such that the temperature inside the cylinder remains constant. Calculate the work input during this process.
Q2/ A mass of 2.4 kg of air at 150 kPa and 12°C is contained in a gas-tight, frictionless piston–cylinder device. The air is now compressed to a final pressure of 600 kPa. During the process, heat is transferred from the air such that the temperature inside the cylinder remains constant. Calculate the work input during this process. Answer: 272 Kj
3 A 40-L electrical radiator containing heating oil is placed in a 50-m³ room. Both the room and the oil in the radiator are initially at 10°C. The radiator with a rating of 2.4 kW is now turned on. At the same time, heat is lost from the room at an average rate of 0.35 kJ/s. After some time, the average temperature is measured to be 20°C for the air in the room, and 50°C for the oil in the radiator. Taking the density and the specific heat of the oil to be 950 kg/m3 and 2.2 kJ/kg-°C, respectively, determine how long the heater is kept on. Assume the room is well sealed so that there are no air leaks. The gas constant of air is R = 0.287 kPa-m³/kg-K (Table A-1). Also, c = 0.718 kJ/kg-K for air at room temperature (Table A-2). Oil properties are given to be p = 950 kg/m³ and Cp = 2.2 kJ/kg.°C. 3 10°C Room Radiator The heater is kept on for Q min. 4
5-62 Refrigerant-134a is throttled from the saturated liquid state at 700 kPa to a pressure of 160 kPa. Determine the tem- perature drop during this process and the final specific vol- ume of the refrigerant. Answers: 42.3°C, 0.0345 m³/kg P₁ = 700 kPa sat. liquid R-134a P₂ = 160 kPa FIGURE P5-62
A 12-ft3 rigid tank contains refrigerant-134a at 30 psia and 55 percent quality. Heat is transferred now to the refrigerant from a source at 120°F until the pressure rises to 50 psia. Assuming the surroundings to be at 75°F, determine the amount of heat transfer between the source and the refrigerant.
Air in a closed-piston cylinder is initially at 100 kPa and 27°C. It is then compressed until the pressure reaches 2 MPa in a polytropic process with n = 1.3. Determine how much boundary work in kJ/kg must be supplied into the system to make this process possible. Round your answer to the nearest whole number.
A piston–cylinder device contains 5 kg of steam at 1008C with a quality of 50 percent. This steam undergoes two processes as follows: 1-2 Heat is transferred to the steam in a reversible manner while the temperature is held constant until the steam exists as a saturated vapor. 2-3 The steam expands in an adiabatic, reversible process until the pressure is 15 kPa. (a) Sketch these processes with respect to the saturation lines on a single T-s diagram. (b) Determine the heat transferred to the steam in process 1-2, in kJ. (c) Determine the work done by the steam in process 2-3, in kJ.