Chapter 5, Problem 5.5E

2. Calculate the annual (365 days) fuel consumption (kg) of the person who owns a car. The maximum output of a car is 100kW, the efficiency of the car is 25%, the average load rate is 20%, the average usage time per day is 2 hours, and the calorific value of the fuel is 10kcal/g. (1cal = 4.2J)

A diesel power station has a fuel consumption of 0.37 lb/ kWh. The calorific value of fuel being 30,000 Btu/lb. Determine the engine efficiency if the generator efficiency is 95%?

Define Renewable energies such as wind are called “green energy” since they emit no pollutants or greenhouse gases.

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7.66 Referring to the discussion of Sec. Z.6.2 as required, evaluate the exergetic efficiency for each of the following cases, assuming steady-state operation with negligible effects of heat transfer with the surroundings: a. Turbine: Wer 1200 hp, e 250 Btu//lb, eg = 15 Btu/lb, m 240 lb/min. b. Compressor: Wev/m=-105 kJ /kg, e = 5 kJ/kg, eg = 90 kJ/kg, m 2 kg /s. c. Counterflow heat exchanger: mh = 3 kg/s, me 10 kg /s, ef = 2100 kJ/kg, e = 300 kJ/kg, É = 3.4 MW 10 lb /s, m3 15 b /s, en = 1000 Btu/Ib, eg = 50 Btu/Ib, eg = 400 Btu/lb d. Direct contact heat exchanger: m1

EXPLAIN THE THE DECREASE OF EXERGY PRINCIPLE AND EXERGY DESTRUCTION.

boiler furnaces with air fed in 20% excess or more, while today improved boiler designs enable the use of 5-10% excess air. Discuss as many possible negative consequences as you can think of for the air-to-fuel ratio being (i) too low and (ii) too high.

Describe the Carnot Principles and briefly discuss the importance.

The cycle involved in the operation of an internal combustion engine is called the Otto cycle. Air can be considered to be the working substance and can be assumed to be a perfect gas. The cycle consists of the following steps: I) Reversible adiabatic compression from A to B. 2) Reversible constant-volume pressure increase from B to C due to the combustion of a small amount of fuel. 3) Reversible adiabatic expansion from C to D. 4) Reversible and constant-volume pressure decrease back to state A.   Determine the change in entropy (of the system and of the surroundings) for each step of the cycle and determine an expression for the efficiency of the cycle, assuming that the heat is supplied in Step 2. Evaluate the efficiency for a compression ratio 10:1. Assume that in state A, V=4.00 dm', p= 1.00 atm, T= 300 K, that VA = 10 Vb, pc/pb = 5, and that Cp.m = (7/2)R Note that R = 8.314 J K-1 mol-1 and dm = 10-1 m.