Module Five Lesson Two Assignment_ Real Life Predictions (12)

Suppose that a new gasoline engine has been invented which can operate at the maximumthermodynamic efficiency (rather than the 25% or so which characterize most realisticengines). The burned fuel reaches about 2100 degrees C inside the engine and a 50 L gas tank has about2 GJ of fuel energy. If the engine must supply 30 hp to keep the car at a steady speed on the highway, how long will a tank of gas last?

From a combustion point of view, how does a diesel engine differ from a gasoline engine?

1. 451.8 C 2. 548.04 kw 3. 765.526 K Need last three

What is the maximum thermal efficiency possible for a power cycle operating between 600°C and 110°C? (A) 47% (B) 56% (C) 63% (D) 74%

Ts diagrams for two reversible thermodynamic power cycles are shown in the following fig- ure. Both cycles operate between a high temperature reservoir at 500 K and a low temperature reservoir at 300 K. The process on the left is the Carnot cycle described in Section 2.9. The process on the right is a Brayton cycle, which is similar to a Carnot cycle, except that the two steps (state 1 to state 2) and (state 3 to state 4) are at constant pressure. Which cycle, if either, has a greater efficiency? Explain.

shown below is P-V diagram for a reversible cycle enclosed by 4 reversible process curves.  The curve 1-2 and the curve 3-4 are  reversible isothermal processes, and the curve 2-3 and the curve 1-4 are reversible adiabatic processes. If the cycle direction is counter clockwise, answer the question below. What is the cycle?____             A. Carnot cycle   B. ideal heat engine cycle   C. Carnot refrigeration cycle   D. Reversed refrigeration cycle

5. An engine does 10J of work and exhausts 15J of waste heat. а. Draw an energy transfer diagram for this engine b. What is the engine's efficiency? c. If the cold reservoir temperature is 20°C, what is the minimum possible temperature in °C of the hot reservoir?

Do complete problem with all parts

A=83 B=87

Thermodynamics fill in the blank: 1) Among the principal irreversiblilities of a gas turbine power plant, the most significant source of irreversibility by far is ______________. 2) Cooling a gas as it is compressed would reduce the work input required during compression, but achieving a heat transfer rate high enough to effect a significant reduction in work is difficult to achieve in practice. A practical alternative is to introduce multiple stages of compression with heat exchangers called _______________ between the stages.

All real engines are less efficient than the Carnot engine because: a.they do not operate through the Otto cycle. b.they do not operate through a reversible cycle. c.the working substance does not maintain a constant volume through the cycle. d.the working substance does not maintain a constant pressure through the cycle. e.the working substance does not maintain a constant temperature through the cycle.

An inventor looking for financial support comes to you with an idea for a gasoline engine that runs on a novel type of thermodynamic cycle. His design is made entirely of copper and is air-cooled. He claims that the engine will be 85% efficient. Should you invest in this marvelous new engine?

Two reversible cycles operate between hot and cold reservoirs at temperatures TH and TC, respectively. (a)If one is a power cycle and the other is a refrigeration cycle, what is the relation between the coefficient of performance of the refrigeration cycle and the thermal efficiency of the power cycle? (b)If one is a refrigeration cycle and the other is a heat pump cycle, what is the relation between their coefficients of performance?