Most solar-thermal collectors are ‘glazed’ meaning they are contained within a shallow box with a glass cover to insulate the absorber from heat loss by convection (e.g. from wind) while allowing the majority of the solar radiation to pass through to the absorber. Flat-plate solar collectors are typically tilted to optimise their solar energy absorption. The tilt angle affects the rate at which heat is lost from the collector due to natural convection. A collector is 0.96 m high and 2.4 m wide and has a gap between the absorber and glass of 24 mm. Assuming the absorber plate (the surface that heats the water) is maintained at 90 °C and the inside surface of the glass cover is maintained at 45 °C, calculate the rate of heat loss by natural convection between the absorber plate and glass cover for tilt angles of 0°, 45° and 90° from horizontal.

Give an example of how annealing is used in an engineering application. Also, briefly explain how and why the mechanical properties—for a metal—of yield strength, ductility, hardness, Young’s modulus, ultimate tensile strength, and toughness are different for a cold worked metal vs a metal that has been annealed at a relatively high temperature for a relatively long time (must talk about grain size).

What are the advantages and disadvantages of the PI controller, PD controller and PID controller ?

PLEASE DO IT IN A COMPUTER

ADVANCED DYNAMICS AND CONTROL SYSTEMS

What process is similar to powdered metallurgy in ceramic materials?

For the following, assume air is an ideal gas with constant specific heats at 300K. Find the work and heat transfer and state whether they are into or out of the air.

In an open system, air is heated at constant pressure from 27°C, 400 kPa to 500K.

w = 0 kJ/kg, q = 201 kJ/kg

In a closed system, air is heated at constant pressure from 27°C, 100 kPa to 500K.

w = 57.4 kJ/kg, q = 201 kJ/kg

Describe the difference between a point defect and a line defect and the effects on the crystal structure. Give an example and sketch of each of the two types.

Describe the process of interdiffusion. How is this process affected by temperature and how is it affected by the crystal structure of the material?

A piston–cylinder assembly contains 2 lb of water, initially at 100 lbf/in.2 and 600°F. The water undergoes two processes in series: a constant-pressure process followed by a constant volume process. At the end of the constant-volume process, the temperature is 300°F and the water is a two-phase liquid–vapor mixture with a quality of 50%. Neglect kinetic and potential energy effects. Determine the work and heat transfer for each process, all in Btu.

A long cylindrical rod of 100 mm radius consists of a nuclear material (k = 0.5 W/m-K) generating 24 kW/m3 uniformly throughout its volume. The rod is enclosed within a tube having an outer radius of 200 mm and a thermal conductivity of 4 W/m-K. The outer surface is exposed to a convection environment at 100 C with a convective heat transfer coefficient of 20 W/m2-k.

a) Calculate the heat rate per unit length being convected away from the rod.

b) Calculate the interface temperature and the outer surface temperature.

c) Show a plot of temperature vs. radius from r = 0 to r = 300 mm.

Write a discussion and conclusion for simple harmonic motion.

A long cylindrical rod of 100 mm radius consists of a nuclear material (k = 0.5 W/m-K) generating 24 kW/m3 uniformly throughout its volume. The rod is enclosed within a tube having an outer radius of 200 mm and a thermal conductivity of 4 W/m-K. The outer surface is exposed to a convection environment at 100 C with a convective heat transfer coefficient of 20 W/m2-k.

a) Calculate the heat rate per unit length being convected away from the rod.

b) Calculate the interface temperature and the outer surface temperature.

c) Show a plot of temperature vs. radius from r = 0 to r = 300 mm.

Problem 3.030 SI Using the tables for water, determine the specified property data at the indicated states. (a) At p = 3 bar, v = 0.35 m3/kg, find T in °C and u in kJ/kg. (b) At T = 320°C, v = 0.23 m3/kg, find p in MPa and u in kJ/kg. (c) At p = 28 MPa, T = 700°C, find v in m3/kg and h in kJ/kg. (d) At T = 10°C, v = 10 m3/kg, find p in kPa and h in kJ/kg.

Different nations have proposed different responses to climate change. For example:

-The United States has proposed to inject aerosols into the stratosphere as a means of solar radiation management.

-China has proposed to implement solar radiation management using reflectors in space.

-Scotland has proposed marine cloud brightening for solar radiation management.

(etc. etc….)

Choosing any one of the above examples, describe in more detail how the response could be implemented. Outline the likely risks covering technical, social and economic perspectives.

* PLEASE CHOOSE THE EASIEST AND SHORTEST ANSWER .

*PLEASE TYPE THEM ON COMPUTER