Chapter 8, Problem 8.14P

Carnot heat engine which produces 10 kJ of work for one cycle has a thermal efficiency of 50 percent. The working fluid is 0.50 kg of air, and the pressure and volume at the beginning of the isothermal expansion are 7 bars and 0.119 m3, respectively. Find  a. the maximum and minimum temperatures for the cycle, in degrees Kelvin,  b. the net work , and c.  the volume at the end of the isothermal expansion process , in m3.

A proposed cyclic heat engine will accept 300 J of heat from a hot reservoir at 800 K, output 250 J of work to the surroundings, and reject 50 J of heat to a cold reservoir at 300 K. According to the 2nd law of thermodynamics, which of the following statements is correct? The system is possible but irreversible. The system is impossible. The system is possible and reversible.

Two engines, one of the auto cycle type and the other of the diesel type, have the same compression ratio and the same amount of heat entering, which one is more efficient? Prove it with a diagram.

A heat engine operating between two reservoirs receives energy Q,=2100 KJ by heat transfer from a hot reservoir(source) at T,= 2000 K and rejects energy Q2=500 KJ by heat transfer to a cold reservoir (sink) at T2= 400 K. Determine the reversible and irreversible efficiencies of heat engine. Calculate ideal and practical efficiency To be: Q, = 2000KJ Q2 = 400KJ -Calculate the reflexive work Wrev -Calculate practical (real) work

. Consider three reservoirs that are TH = 473.2 K, TL = 293.2 K and TI = 277.2 K.  A Carnot heat engine can be reversed and used as either a heat pump or a refrigerator.  In the case of a heat pump the heat flow to the higher temperature reservoir is the desired output and it is used to heat a room or building.  In the case of the refrigerator the desired energy flow is the heat in from a region to be cooled.  For the heat pump or refrigerator, the work input is provided by electricity.  For this information answer the following questions: a) Calculate the Carnot Efficiency of a heat engine that operates between TH and TL. b) A room is maintained at a constant temperature of 20 C and has a heat loss of 20,000 W. Consider this room for a period of 3 hours. The surroundings are at a temperature of TI.  In one option the room is heated using resistive heaters that are operated with electricity.  b1)Determine the electrical energy input to these heaters. b2)Determine the efficiency of…

The efficiencies of all reversible heat engines operating between the same two reservoirs are the same?

What is the COP of a reversible refrigerator operating between 0 degrees C and 26 degrees C?

4- A thermoelectric refrigerator is powered by a 12-V car battery that draws 3 A of current when running. The refrigerator resembles a small ice chest and is claimed to cool nine canned drinks, 0.350-L each, from 25 to 3°C in 12 h. Determine the average COP of this refrigerator.

The compression ratio of an engine working on the constant volume cycle is 9.3. At thebeginning of compression, the temperature is 31°C and at the end of combustion thetemperature is 1205°C. Taking the compression and expansion process to be adiabatic andthe value of k as 1.4. Determine the following a. T2. 741.7657 Kb. T4. 605.733 Kc. Thermal Efficiency. 59.02%