Heat Engines - Spring 2019 - 3 slides

Thermodynamics

A closed thermodynamic system undergoes a cycle comprising four processes 1- 4. The following amount of heat is transferred through the system boundaries: Process 1: 50 kJ heat added to the system Process 2: 80 kJ heat removed from the system Process 3: 100 kJ heat added to the system Process 4: 40 kJ heat removed from the system What is the net work done in this cyclic process?

Thermodynamics. please answer the 2 questionn, i will give a good feedback. thank you,  show solution step by step.

A coal-burning steam locomotive heats steam to 180 degrees Celsius and exhausts it at 100 degrees Celsius. During 1 second of operation, it consumes 500 million J of energy from the burning coal. According to Table 1 in the picture, how much work can be obtained from this locomotive during 1 second of operation under ideal conditions (no friction or other imperfections)?

During a warm summer night, the air inside a house is maintained at a fixed temperaturevia an air conditioning system. Separating the inside air from the outside air is a plane wall.The inner surface of the wall exchanges energy with the air inside the house via convection;the outer surface of the wall exchanges energy with the surrounding air via convection andthe night sky via radiation. Known system parameters are listed below.Inner air temperature ?? = 26°CSurrounding air temperature ?∞ = 33°CNight sky temperature ?? = 4°CWall thermal conductivity ?Wall-air convection coefficient ℎ = 30 W/m2-KWall emissivity ? = 0.85Wall thickness ?a) Set up the equations that you allow you to calculate the heat flux through the wall.Keep everything symbolic and be careful with your heat transfer directions.Hint: If the AC is on, what does that tell you about the net direction of heat transfer?b) Write a computer script that calculates the heat flux through the wall for 20 values ofthe ratio of the…

Given the following situations, tell whether it applies the first law of thermodynamics or second law of thermodynamics. Draw a smiley face if applies the first law and a heart if it applies the second law. 1. Food digestion 2. Rusting of iron 3. Photosynthesis 4. Using aircon during summer 5. Simple motor 6. Growing younger 7. Plugging TV to watch a program 8. Riding a bicycle 9. Generator 10. Heat flows from lower to higher temperature

PLEASE ANSWER IT WITH SOLUTION STEP BY STEP. Thermodynamics. answer it in 1hr.

A heat engine absorbs heat from the combustion of gasoline at 2200°C. The gasoline has a specific gravity of 0.8 and a heat of combustion of 11,200 cal/gram. The engine rejects heat at 1200°C. The maximum work in calories that can be obtained from the combustion of 1 liter gasoline isA. 3.62 E6 calB. 4.53 E4 calC. 3.78 E5 calD. 4.22 E6 cal

In the United States, energy for household heating is generally sold using English units, e.g., therm, gal, and cord. A house in Wisconsin uses 1200 therms of thermal energy during the heating season. Calculate the cost of fuel if the furnace uses (a) natural gas with an efficiency of 70%; (b) No. 2 fuel oil, efficiency 65%; (c) kerosene, efficiency 99.9% (unvented); and (d) wood with l5% moisture with an efficiency of 50%. Use the data in Tables 2.2, 2.7, and 2.13. The efficiencies are based on the HHV. Assume the cost of natural gas is $8/MBtu, the cost of No. 2 fuel oil is $3/gal, the cost of kerosene is $3.50/gal, and the cost of wood is $100/cord. Assume the bulk density of cord wood is 30 lbm/ft3 .

72 THERMODYNAMICS 1 6. Determine the energy required to accelerate a 1300- kg car from 10 to 60 km/h on an uphill road with a vertical rise of 40 m.

1. Is a temperature difference necessary to operate a heat engine? State why or why not. 2. Definitions of efficiency vary depending on how energy is being converted. Compare the definitions of efficiency for the human body and heat engines. How does the definition of efficiency in each relate to the type of energy being converted into doing work? 3. Why-other than the fact that the second law of thermodynamics says reversible engines are the most efficient-should heat engines employing reversible processes be more efficient than those employing irreversible processes? Consider that dissipative mechanisms are one cause of irreversibility. 1. (a) What is the efficiency of a cyclical heat engine in which 75.0 kJ of heat transfer occurs to the environment for every 95.0 kJ of heat transfer into the engine? (b) How much work does it produce for 100 k) of heat transfer into the engine? 2. The engine of a large ship does 2.00×10°J of work with an efficiency of 5.00%. (a) How much heat…

Examine the performance of engineering devices in light of the second law of thermodynamics.

Q A horizontal piston-cylinder assembly contains 2.00 kg of a fluid. The assembly is fitted with both a heater and a paddle wheel. It is found that the fluid undergoes an expansion from state 1 to state 2. During the process, the paddle wheel transmits 16.4 kJ of mechanical energy (Wp.w.) to the fluid via mixing, and the heater supplies 83 kJ of thermal energy (Q) to the fluid. The specific internal energy changes from U1 = 2386.6 kJ/kg to U2 = 2409.1 kJ/kg during the process. Determine the work done by the steam on the piston during the process (Wpiston) (kJ). Your Answer: 45°F hp Insert * 24 % 8. 4 R H J K D F CV B N M

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Your house has an electric water heater. Several friends are visiting you over the weekend and they are taking consecutive showers. Assume that at the maximum heating level, the heater uses 50 kW of electricity. The water use rate is a continuous 4 gallons per minute with the new water saving showerhead you recently installed. Your very old showerhead had used 7 gallons per minute. You replaced the showerhead because you learned that heating water was the second highest energy use in your home. By slowing the flow of water through the heater, the water temperature should increase to a higher temperature. (a) What is the change in temperature (T) for the old showerhead? (b) What is the change in temperature (T) for the new showerhead? Assume the system is at steady sate, and all of the 50 kW energy used is heating the water.

An office heater puts out 2090 Btu (British thermal units) of energy in the form of heat per hour. Given that 1 Btu=1.055 kJ,how many megajoules of energy in the form of heat can be produced per year (365 days) by the heater, assuming continuous operation?

please answer it answer it in 1hr.

Thermodynamics question 3 in need the answer please