3. A heat engine operating between a geothermal steam source at 205°C and a riv-er at 18°C achieves an efficiency of 22%. What percentage of its theoretical max-imum efficiency is it achieving? 5. A certain engine is filled with gasoline that contains chemical energy nwhen the engine is started, it begins transforming that chemical energy intesmechanical energy. Over the course of a few seconds, the engine transforms8,000J of chemical energy, but 4,000) of that energy is 'wasted' in the form ofthermal energy.2 How much energy does the engine transform into useful mechanicalenergy during these few seconds?b. Calculate the efficiency of this engine.

Answered: Image /qna-images/answer/245547be-b1d3-4690-a8ad-7e1e2a1559b6.jpg

Answered: 3. A heat engine operating between a…

3. A heat engine operating between a geothermal steam source at 205°C and a riv- er at 18°C achieves an efficiency of 22%. What percentage of its theoretical max- imum efficiency is it achieving?

Refrigeration and Air Conditioning Technology (MindTap Course List)

8th Edition

ISBN:9781305578296

Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Chapter45: Domestic Refrigerators And Freezers

Section: Chapter Questions

Problem 12RQ: Refrigerators currently being manufactured in the United States are using______as their refrigerant.

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Since Lucas is an engineer familiar with thermodynamics. He decided to create his own heat engine at home to avoid paying for electricity. He created a small, makeshift heat engine for trial. The combustion of his fuel. diesel, reaches a temperature of 750°C, while waste heat is disposed to the atmosphere at 50°C. He, then connected a generator and a heat pump to the heat engine to check the amount of power being produced. Assume that the heat pump will be used to warm his room to 25°C, while the outside temperature is at 5°C. Lucas' rooms loses 85,000 kJ/hr of heat. And, 25% of the heat engine's power output goes to the heat pump. How much diesel (in kg) needs to be burned by the heat engine to maintain the temperature in Lucas' room? Assume carnot heat engine and heat pump. If the natural gas has a heating value of 22,000 BTU/lb.
A heat pump operates with Refrigerant 134a as the working fluid. You are required to analyze its performance, and compare it with Camot heat pump. The data of the heat pump is as under: 23 - Thermodynamies-II Page 1 of 3 The heat pump is presently providing heating at a rate of 12 kW to maintain the interior of a building at 20°C. Outside temperature is 5°C. The refrigerant enters the compressor at 2.4 bar and increases the pressure to 8.0 bar. Efficiency of the compressor is 80%. a Temperatures at the principal states of the cycle, each °C b. Power input to the compressor, in kW c. Coefficient of performance Relate its performance with the specifications provided by the vendor i.e. COP = 8.5 and identify the possible reasons of differences. Draw Ts diagram
Calculate the thermal efficiency of a Carnot cycle heat engine operating betweenreservoirs at 300℃ and 45℃
SUBJECT: THERMODYNAMIC COURSE: II ASSI.LACTURE: NATIQ ABBAS Example 2:- Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 MPa and -10°C at a rate of 0.05 kg/s and leaves at 0.8 MPa and 50°C. The refrigerant is cooled in the condenser to 26°C and 0.72 MPa and is throttled to 0.15 MPa. Disregarding any heat trans fer and pressure drops in the connecting lines between the components; determine (a) the rate of heat removal from the refrigerated space and the power input to the compressor, and (b) the coefficient of performance of the refrigerator. Solution: - P 0.14 MPa T=-10 C dut 246.36 kJ/kg OF P 0.8 MPa h2 = 286.69 kJ/kg P 0.72 MPa T= 26 C h3 = 87.83 kJ/kg h3 = h = 87.83 KJ/kg h4 = h3 (throttling) h4 87.83 kJ/kg 0.8 MPa 0.72 MPa/ 26 C 0.15 MPa 0.14 MPa -10°C SUBJECT: THERMODYNAMIC COURSE: II ASSI.LACTURE: NATIQ ABBAS SAMARRA RING
SUBJECT: THERMODYNAMIC COURSE: II ASSI.LACTURE: NATIQ ABBAS Example 2:- Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 MPa and -10°C at a rate of 0.05 kg/s and leaves at 0.8 MPa and 50°C. The refrigerant is cooled in the condenser to 26°C and 0.72 MPa and is throttled to 0.15 MPa. Disregarding any heat trans fer and pressure drops in the connecting lines between the components; determine (a) the rate of heat removal from the refrigerated space and the power input to the compressor, and (b) the coefficient of performance of the refrigerator. Solution: - P 0.14 MPa T=-10 C 212 h 246.36 kJ/kg da OF SAMARRA P 0.8 MPa VER h2 = 286.69 kJ/kg O P 0.72 MPa T= 26 C hg = 87.83 kJ/kg h3 =h = 87.83 KJ/kg h4 = h3 (throttling) h4 87.83 kJ/kg 0.8 MPa 50°C 0.72 MPa/ 26 C 0.15 MPa 0.14 MPa -10°C SUBIECT: THERMODYNAMIC COURSE: II ASSI.LACTURE: NATIQ ABBAS RING
Since Lucas is an engineer familiar with thermodynamics. He decided to create his own heat engine at home to avoid paying for electricity. He created a small, makeshift heat engine for trial. The combustion of his fuel, diesel, reaches a temperature of 750°C, while waste heat is disposed to the atmosphere at 50°C.He, then connected a generator and a heat pump to the heat engine to check the amount of power being produced. Assume that the heat pump will be used to warm his room to 25°C, while the outside temperature is at 5°C. Lucas’ rooms loses 85,000 kJ/hr of heat. And, 25% of the heat engine’s power output goes to the heat pump. How much diesel (in kg) needs to be burned by the heat engine to maintain the temperature in Lucas’ room? Assume carnot heat engine and heat pump. If the natural gas has a heating value of 22,000 BTU/lb. *Round off all answers to four decimal places*
Thermodynamics: A refrigeration unit using Refrigerant-134a is used to maintain a certain space at –15°C. The condenser rejects heat (?H) to cooling water that enters the condenser at 15°C at a rate of 0.2 kg/s and leaves at 35°C (all as saturated liquid water). The superheated refrigerant enters the condenser at 0.8 MPa and 40°C and leaves as a saturated liquid at the same temperature. If the compressor consumes 4.5 kW of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load (?̇L), (c) the COP.
Describe the function and components of a heat engine?
A cyclic heat engine operates between a source and sink that are respectively attemperatures of 1000 0C and 50 0C. Draw the diagram, calculate the efficiency of the heatengine and the rate of heat rejection per kW net output of the engine.
1.A vapor-compression refrigeration system, using R-134a, is being used to keep a food storage room under desired cold temperature. At steady state conditions, the evaporator temperature is 0°C, and the condenser temperature is 48°C. The cooling load on the refrigeration system is 8 tons of refrigeration. Calculate the refrigerant flow rate, the compressor power if the compressor efficiency is 78%, and C.O.P.
A heat engine is assumed to operate on a Carnot cycle. It receives 900kJheat from a high temperature reservoir at 550oC and rejects heat to a lowtemperature reservoir at 30oC.a. Calculate the thermal efficiency of the cycle.b. What is QH and QL?c. What is the net work produced by this cycle?d. Does this process violate Kelvin-Plank statement? Explain.e. An inventor claimed that he built a heat engine operating between the same reservoirs that give a thermal efficiency of 80%.Comments about his claim.f. Draw this process on a Ts diagram with proper labelling.g. If the cycle is reversed and operated as a heat pump, calculate itsperformance.
Why heat engines are intentionally equated at high temperatures?