Problem 1. Brayton Cycle

A Brayton cycle engine with air runs between 1700K and 800K. The air enters the compressor at 95kPa and leaves at 580kPa. The mass flow rate is 300 kg/s, and the isentropic efficiencies of the compressor and turbine are 90% and 95% respectively. Find the net work output of the cycle and thermal efficiency of the cycle. How many MW of electrical energy is generated if the generator efficiency is 90%?

Problem 2. Flat-Plate Solar Collector

Collector tests produce the following results:

This collector operates for a day under the conditions listed in the table. (l_T is in kJ/m² and temperatures are in C). Complete the table.

Hour	l_T	T_a	T_i	q_b	S	Q_u/A_c	h
8-9	314	-8.3	31	58
9-10	724	-1.7	29.6	45
10-11	1808	1.7	27.1	34
11-12	2299	3.3	30.5	26
12-1	1926	5.6	35.7	26
1-2	420	7.2	34.3	34

From 2pm on, radiation is negligible.

Problem 3. Wind Turbine

Determine the annual energy output from a 3 bladed wind turbine with a rotor diameter of 10 m using optimum tapered and twisted blades rotates at a speed of 30 rpm. For wind speeds from 15 km/h to 40 km/h, calculate the power for the system. Assume an angle of attack of 5 degrees for the airfoil. Plot the power as a function of wind speed.

Problem 4. Fuel Cell

Using the data from the example problem worked out in Lecture 20, design a system to deliver 32 volts. Find the number of cells required and estimate the net power output.