ENGR 211 K THERMODYNAMICSHOMEWORK # 1

[1] You are tasked with designing the steam loop for a power station. Water is boiled to steam, passed through a steam turbine, and then condensed back into liquid using a heat exchanger cooled by water from a nearby water source (lake, river, ocean etc.). What recommendations would you make regarding the temperature and pressure of the boiler and the condenser to maximize the efficiency of the power plant? Discuss your recommendation and rationale in detail including the limits where your recommendation no longer holds and the assumptions you make regarding the efficiency of components such as pumps, heat exchangers etc. Note: The Carnot efficiency of a heat engine (the theoretical maximum efficiency a heat engine can achieve) is equal to 1 – Tc/Th , where Tc is the temperature of the cold reservoir (heat sink) and Th is the temperature of the hot reservoir (heat source).

[2] A tire has a volume of 0.045m3 at − 8°C and 200 kPa gage. If the pressure increase to 300 kPa gauge and volume decrease to 0.035m3, find the final Temperature.

[3] In a heat exchanger, 10 kg/s of water enters the cold side at 25°C and leaves at 70°C. Find the rate required for water to enter the hot side at 90°C and 150kPa, and leave at 30°C. (Assume there is no pressure drop in the heat exchanger)

[4] Using the Temperature-Entropy diagram for water above (with isobar lines shown in black), a) at what pressure will water just begin to boil that has an entropy of roughly 0.1 btu/lbm-R and a temperature of 550 Rankine? b) At what entropy will water at this pressure just be fully converted to steam? c) At what temperature in Fahrenheit does the water fully turn to steam? ([°F] = [°R] − 459.67)?