Questions & Answers

2. A house at 48° N latitude has a roof that faces due south, and is elevated to an angle of 28°. A solar panel is mounted to the roof. What is the angle of incidence between the sun and the array at 1 p.m. on June 1

Need to work on the research part, which includes the material used, the condition, and the preparation of switchgrass to produce biofuel in a more technical aspect. Then, the technology needs to transfer the switchgrass to biofuel by addressing and analyzing the parameter and conditions. There are three kinds of technology biochemical, thermochemical, and combined between both.

Course work: Design a heat pump to heat the James Watt Building South This course work assignment is part of the final assessment of this course, and it accounts for 25 marks (25% of the total assessment). Objective: The peak heating demand of the James Watt Building South is assumed to be 400 kW. Its heating network system delivers heat by pumping hot water at 80 *C through radiators. The measured river water temperature for most of the heating season is in the range 6-10 °C. After extracting heat, the cold water should be returned to the river with a temperature no less than 4 °C. You are expected to apply the learned thermodynamics knowledge and skills to conduct a conceptual design of a two-stage water source heat pump to extract heat from the water of river Kelvin to heat the James Watt Building South.

1 The temperatures of the hot and cold reservoirs are: = 1050°F = 565°C = 839 K T=554°F = 295°C = 563 K This gives an ideal Carnot efficiency of 100 ×(1-563K/839K) = 33 % Thus the total solar insolation must be 1 GW/0.33 = 3 GW. The installation in Figure 9.4 is in California and from Figure 8.2 the average insolation can be estimated to be 225 W/m. The area needed to produce the necessary power is 1.3 x 10 m. For a circular array this corresponds to an area about 4 km in diameter. This is too large of an area. Why?

2. Problem 10.1 (10 pts) The power output in watts is given as P = (0.602 kg/m³)4 nv³ The velocity as a function of height is

3. Problem 10.2 (10 pts) Area per turbine is (3.14) x (5 m) = 78.5 m² per turbine. The power per turbine will be P = 4.08 × 10³ W The average spacing of the wind turbines downwind will be 10 times the rotor diameter or 100 m and the crosswind spacing will be 3 times the rotor diameter or 30 m. Thus each turbine will occupy a land area of (30 m) x (100 m) = 3000 m². Thus, 1 km² square of land area will accommodate (10 m/km)/(3000 m²) = 333 turbines with a total output of 1.36 MW (b) From equation (9.3), P = 30.2 MW. This is more than 20 times the wind power output.

4. Problem 10.3 (10 pts) P = (0.602 kg/m )nAv. Solving for n gives

5. Problem 10.5 (10 pts) During each period the power will be: 3 P = (0.602 kg/m³)m.4v = (0.602 kg/m³) × (0.37) × (3.14) × (10 m)²,³ = (69.9 kg/m) v³ For the different periods the power available will be: for 4 h at 2 m/s →→ (69.9 kg/m) x (2 m/s)³ = 560 W for 16h at 8 m/s →→ (69.9 kg/m) x (8 m/s) = 35790 W etc. etc. The energy generated during these periods is the power times the duration as for 4 h at 2 m/s → (0.560 kW) x (4 h) = 2.2 kWh for 16h at 8 m/s → (35.79 kW) × (16 h) = 572.6 kWh etc., etc. Adding these gives the total energy over the 24 h period is E= 1494 kWh The average power is, therefore P = 62.2 kW

Determine the condensing and evaporating temperatures for your heat pump. Please note that the condensing temperature should be a few degrees higher than the hot water temperature, while the evaporating temperature should be a few degrees lowered than the river water temperature. Please provide a justification for your choice. • Select a refrigerant and provide a justification of your selection. You should consider their ozone depletion potential, global warming potential, toxicity, flammability, cost, etc. Design a two-stage heat pump. You can select a cycle layout from those that we covered in lectures. Alternatively, you can design your own cycle layout. • You should sketch the schematic diagram of your design, and the corresponding pressure-enthalpy and temperature-entropy diagrams. • Find the thermophysical properties and conduct a cycle analysis. Show all the equations and calculations including COP, mass flowrate of refrigerant, power consumptions of compressors, heat extraction rate from river, etc. Calculate the minimum mass flow rate of water that you need to extract from the river to provide the required heat while maintaining the return temperature above 4 °C. • Select the type of compressor, expansion device, heat exchangers for the evaporator and condenser, and provide your justification.

EG-111 Technical Report Topic Assignments This list details the topic selected for your technical report by your student number. You may NOT chose your own report topic, and your topic may NOT be changed from this list. Topic 1: Types of fuel cells and their applications

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