Reference no: EM132541417 , Length: 20 pages

EA210MED Engineering Science - Emirates Aviation University

Assignment - Thermofluids

Scenario:
You have recently joined ABC Design Company as Technical Engineer. Your supervisor has requested you to construct a report as part of your training. You are required to provide a sound explanation of the theory and calculate specific parameters related to thermodynamic systems and heat transfer.

Part 1
The fundamental concepts, principles and definitions in terms of heat and work are essential for your work, as such you are required to complete the following tasks:

1. Define and explain the following concepts. Use equations and diagrams to supplement your answer:
a. Phases of Matter
b. Phase Change
c. Latent heat of Fusion & of Vaporisation

2. The graph given below shows the relation between given heat and change in the temperatures of the three matters having same masses. Compare the specific heat capacities of these matters.

3. A student added lumps of ice to cool a Lemonade. He discovers that 80g of ice at a temperature of 0°C cools 0.25 kg of lemonade from 26°C to 5°C. The latent heat of fusion of ice is 0.33 Mi/kg and the specific heat capacity of water is 4.2 kJ/kg K. Determine:
a. The energy gained by the ice in melting
b. The energy gained by the melted ice
c. The energy lost by the lemonade
d. A value for the specific heat capacity of the lemonade

4. Two taps fill the water tank with different flow rates. Tap A fills the tank in 1 hour and tap B fills the tank in 3 hour If we open two taps 10°C 50°C together, find the final temperature of the water in the tank.

Part 2
Gas laws help us understand the properties of a working fluid when it goes through certain changes within a particular thermodynamic system.

1. Your next Part is to define and explain what an ideal gas is and under what conditions does a real gas behave as an ideal gas. Use equations to supplement your answer.

2. Oxygen and hydrogen gas are placed in two different containers connected with a valve. The oxygen gas occupies a volume of 2.75 L and has a pressure of 0.85 atm. The hydrogen gas has a pressure of 1.5 atm and occupies a volume of 2.8 L and. Find the total pressure when the valve between the two containers is opened and the gases are allowed to mix.

3. 1 kg of a gas at a temperature of 450 C and a pressure of 120 KPa occupies a volume of 0.5 m3. If the Cv of the gas =743 ..I/Kg.K Find:
a. The characteristic gas constant
b. The modular mass and relative molecular mass
c. The specific heat capacity at constant pressure
d. The ratio of specific heats

Part 3
Your supervisor further asks you to apply the laws of thermodynamics in the following tasks:
1) Define closed systems and excila in the conditions needed for it to transfer work
2) A furnace is transferring heat to a heat engine at a rate of 90MW. The waste heat is rejected to a nearby river at a rate of 55MW. Determine:
a. The net power output of the engine
b. The thermal efficiency of the engine

3) Water enter the boiler in a steam power plant at a rate of 2kg/s, a velocity of 12m/s and an enthalpy of 650 KJ/Kg where it absorbs 1850 KJ/Kg. the water transform into steam, enter the turbine and exit having an enthalpy of 3710 KJ/Kg and a velocity of 45 m/s. the height difference between the inlet of the boiler and the the turbine exit is 4 m. Considering that the heat loss from the turbine is 750 KJ/Kg and from the boiler 1760 KJ/Kg, and assuming boiler and turbine are a single unit; Calculate the Power capacity of the turbine

4) In a steady flow process, the LP compressor of the engine delivers 0.85 kg/s of air at a temperature of 10°C from inlet conditions of 1 bar and 2°C. The input power is 54 kW and the velocity of the air at the inlet and exit are 12 m/s and 37 m/s, respectively. If for the air, cp = 1005 J/kg K, determine:
i. The specific heat energy loss to the surroundings
ii. The cross-sectional area of the LP corn pressor exit

Part 4
The concept of heat transfer is important to engineers to understand and analyse heat transfer rates across buildings and materials.

1) Define and explain the nature of heat transfer by radiation, using diagrams and equations to support your answer.

2) A loaf bread at 120 2C is cooling in air at 20 2C. The dimension of the loaf is as 10 cm by 12 cm by 20 cm. h = 10 W/m2 K, emissivity of the loaf = 0.76, Kioaf = 0.121 Find: Total heat loss from the bread. Assume that Conduction from the loaf to cooling rack is negligible due to
the small area involved. The heat loss is therefore a combination of convection and radiation.

3) A steel pipe with heat transfer coefficient of 35 W/mK contains flowing water. The outer diameter of the pipe is 95 mm and the wall thickness is 2.5mm. Calculate:
i. The heat loss by convection and conduction per meter length of un-insulated pipe when the water temperature is 25°C, the outside air temperature is -5°C, the water side heat transfer coefficient is 30 KW/m2K and the outside heat transfer coefficient is 20 KW/m2K.
ii. Calculate the corresponding heat loss when the pipe is lagged with insulation having an outer diameter of 150 mm, and thermal conductivity of K = 0.04 W/mK

4) A composite wall is composed of 5 sections as represented in the below diagram. The temperature at the left side is 17°C and at the right side is 75°C and h = 15 W/m2 K on both sides. The coefficient of heat transfer are kl = k3 = 78 W/mK, k2 = 115 WirnK, k4 = 100 WirnK, and k5 = 145 Wirn K. Determine:
i. The total thermal resistance,
ii. Heat transfer rate through the composite.

Attachment:- Engineering Science.rar