Paper Details
An ideal gas undergoes two processes in a pistoncylinder device as follows:
1-2 Polytropic compression from T1 and P1 with a polytropic exponent n and a compression ratio of r = V1/V2.
(a) Sketch the processes on a single P-V diagram.
(b) Obtain an expression for the ratio of the compression-to- expansion work as a function of n and r.
(c) Find the value of this ratio for values of n = 1.4 and r = 6.
A plant engineer wishes to know which of two types of light bulbs should be used to light a warehouse. The bulbs that are currently used cost $45.90 per bulb and last 14,600 hours before burning out. The new bulb (at $60 per bulb) provides the same amount of light and consumes the same amount of energy, but it lasts twice as long. The labor cost to change a bulb is $16.00. The lights are on 19 hours a day, 365 days a year. If the firm’s MARR is 15%, what is the maximum price (per bulb) the engineer should be willing to pay to switch to the new bulb? (Assume that the firm’s marginal tax rate is 40%.)
