Design and Optimization of Thermal Systems Episode 1 Part 7 pptx

122 Design and Optimization of Thermal Systems

several new ideas and materials. What are the important means of

communicating these designs and to which groups within or outside

the company do you need to make presentations?

(a) A very efficient room air-conditioning system

(b) A new radiator design for an automobile

(c) A substantially improved and efficient household refrigerator.

2.24. For the thermal systems in the preceding problem, outline the main

design steps employed by you and your design group to reach optimal

solutions.

2.25. You have just joined the design and development group at Panasonic,

Inc. The first task you are given is to work on the design of a thermal

system to anneal TV glass screens. Each screen is made of semi-trans￾parent glass and weighs 10 kg. You need to heat it from a room temper￾ature of 25°C to 1100°C, maintain it at this temperature for 15 minutes,

and then cool slowly to 500°C, after which it may be cooled more rap￾idly to room temperature. The allowable rate of temperature change

with time, ∂T/∂t, is given for heating, slow cooling, and fast cooling

processes. Any energy source may be used and high production rates

and uniform annealing are desired.

(a) Give the sketch of a possible conceptual design for the system and

of the expected temperature cycle. Briefly give reasons for your

choice.

(b) List the requirements and constraints in the problem.

(c) Give the location and type of sensors you would use to control the

system and ensure safe operation. Briefly justify your choices

(d) Outline a simple mathematical model to simulate the process.

2.26. You are asked to design the cleaning and filtration system for a

round swimming pool of diameter D and depth H. The system must

be designed to run the entire volume of water contained in the pool

through the system in 5 hours, after which a given level of purity must

be achieved.

(a) Give the formulation of the design problem.

(b) Provide a sketch of a possible conceptual design.

(c) Suggest the location of two sensors for purity measurements.

2.27. As an engineer at General Motors Co., you are asked to design an engine

cooling system. The system should be capable of removing 15 kW of

energy from the engine of the car at a speed of 80 km/h and ambient

temperature of 35°C. The system consists of the radiator, fan, and flow

arrangement. The dimensions of the engine are given. The distance

between the engine of the car and the radiator must not exceed 2.0 m

and the dimensions of the radiator must not exceed 0.5 m r 0.5 m r￾

0.1 m

Basic Considerations in Design 123

(a) Give the formulation of the design problem. No explanations are

needed.

(b) Give a possible conceptual design.

(c) If you are allowed two sensors for safety and control, what sensors

would you use and where would you locate these?

2.28. As an engineer employed by a company involved in designing and

manufacturing food processing equipment, you are asked to design a

baking oven for heating food items at the rate of 2 pieces per second.

Each piece is rectangular, approximately 0.06 kg in weight, and less

than 4 cm wide, 6 cm long, and 1 cm high. The length of the oven must

not exceed 2.0 m and the height as well as the width must not exceed

0.5 m.

(a) Sketch a possible conceptual design for the system. Very briefly

give reasons for your selection.

(b) List the design variables and constraints in the problem.

(c) Which materials will you use for the outer casing, inner lining,

and heating unit of the oven? Briefly justify your answers.