Ask Mechanical Engineering Expert

Problem 1

Provide short answers to the following problems:

a) What the essential condition for a heat transfer process to occur?

b) What is a differentiation between the steady state conditions and the thermal equilibrium state?

c) Is it probable for the steady state temperature profile in a plane wall to be nonlinear at steady state? If yes, provide one ex.

d) Why do you feel cooler throughout a windy day than throughout a calm day even though the air temperature is the same?

e) Why it is more likely to get burn through putting a bare hand in boiling water at 100oC then into hot air at 200oC?

f) What is a temperature gradient in an object sitting in a room in that the temperature is maintained constant after a sufficiently long time?

g) Is it probable that the surface temperature of the object from part f) to be different than the room air temperature? If yes, please elucidate why?

h) What is the chief reason for a ground frost (air temperature is greater than zero)? For a given air temperature, is ground frost more likely to occur at windy or calm conditions?

i) What is a differentiation between and opaque and semitransparent object?

j) What is the chief reason for the surfaces of different objects to be dissimilar when they exposed to sunlight?

k) What is the differentiation between the closed and open systems?

l) What is the inherent differentiation between application of conservation of energy over a time interval and at an instantaneous of time?

m) Why the form of the energy balance for a surface of an object at stable and uneven state conditions is the same?

n) What is the main reason irreversible operation of the actual heat engines?

o) What is the result of the power output of the actual heat engine on its efficiency? Please describe.

Problem 2

An experiment to find out the convection coefficient allocated with airflow over the surface of a thick stainless steel casting includes insertion of thermocouples in the casting at distances of 10 mm and 20 mm from the surface.  When the experiment was performed in a well insulated air duct so that the temperature of the walls surrounding the steel surface was the same as the air temperature, the thermocouples evaluated the temperatures of 50°C and 40°C in the steel, correspondingly, when the air and the surrounding wall temperatures were 200oC.

a) If the steel has a thermal conductivity of 15 W/m2K and surface emissivity of 0.95, what is the convection coefficient among the steel and hot air?

b) What are the contributions of the convective and radiation heat fluxes to the steel casting?

In the repeated experiments the duct insulation was removed and even although the hot air temperature was the same as before, i.e., 200oC, the surrounding walls temperature dropped to 20oC. As a consequence the steady state heat flux to the steel casting dropped by 13.3% compared to the first experiment.

c) Supposing the same convection coefficient as the value computed in part a), what would be the temperatures evaluated by the thermocouples?

d) Assume that the steel casting was well insulated from all sides except for surface from which the distance to thermocouples is evaluated. Supposing the same convection coefficient as the value computed in part a), what would be the temperatures of the thermocouples when:

i) The experiment is performed in the well insulated duct at T∞ = Tsurr = 200oC?
ii) The experiment is performed in non-insulated duct at T∞ = 100oC and Tsurr = 20oC?

Mechanical Engineering, Engineering

  • Category:- Mechanical Engineering
  • Reference No.:- M91070

Have any Question?


Related Questions in Mechanical Engineering

The aim of the project is to demonstrate certain aspects of

The aim of the project is to demonstrate certain aspects of engineering materials in different applications. The projects will be assessed on the basis of a written Research Report. The report should clearly show what yo ...

Force exerted by jet on moving cart1 you need to determine

Force Exerted By Jet On Moving cart. 1. You need to determine the velocity of water that comes out from the nozzle of this system. need the equation please formulate the equation. 2. This water will strike a small cart a ...

Mechanical engineering assignment task - solve the given

Mechanical Engineering Assignment Task - Solve the given problem. Task 1 - A spring with a one-turn loop of 40mm mean radius is formed from a round section of wire having 5 mm diameter. The straight tangential legs of th ...

Projectflow processing of liquor in a mineral refining

Project Flow Processing of Liquor in a Mineral Refining Plant The aim of this project is to design a flow processing system of liquor (slurry) in a mineral (aluminum) refining plant. Aluminum is manufactured in two phase ...

Heat transfer and combustionyou will need graph paper a

HEAT TRANSFER AND COMBUSTION You will need graph paper, a calculator, a copy of Appendix 1 from lesson HTC - 4 - 2 and access to steam tables to answer this TMA. 1. A fuel gas consists of 75% butane (C 4 H 10 ), 10% prop ...

Assignment -q1 explain the difference between the

Assignment - Q1. Explain the difference between the metacentric height of a ship during 'Partially Afloat condition and 'Free Floating' condition; aid a sketch to support your answer. Q2. With the aid of sketches, explai ...

Materials behaviour from atoms to bridges assignment -

Materials Behaviour from Atoms to Bridges Assignment - Distributed loads and static equilibrium (Please note: you should show your steps with necessary figures) Q1. Two beam sections are jointed at C and supported at A b ...

Questions -q1 a qualitative estimate of the effect of a

Questions - Q1. A qualitative estimate of the effect of a wind-tunnel contraction (Figure) on turbulent motion can be obtained by assuming that the angular momentum of eddies does not change through the contraction. Let ...

Assignment - machine learning for signal processingproblem

Assignment - Machine Learning for Signal Processing Problem 1: Instantaneous Source Separation 1. As you might have noticed from my long hair, I've got a rock spirit. However, for this homework I dabbled to compose a pie ...

Problem -a long pipe od 1413 mm id 1318 mm kp 20 wmk

Problem - A long pipe (OD = 141.3 mm, ID =131.8 mm, k p = 20 W/m.K) supplies hot pressurized liquid water at 400 K to a heater in a factory. The pipe has an insulation thickness of 100 mm. A new efficient heater replaces ...

  • 4,153,160 Questions Asked
  • 13,132 Experts
  • 2,558,936 Questions Answered

Ask Experts for help!!

Looking for Assignment Help?

Start excelling in your Courses, Get help with Assignment

Write us your full requirement for evaluation and you will receive response within 20 minutes turnaround time.

Ask Now Help with Problems, Get a Best Answer

Why might a bank avoid the use of interest rate swaps even

Why might a bank avoid the use of interest rate swaps, even when the institution is exposed to significant interest rate

Describe the difference between zero coupon bonds and

Describe the difference between zero coupon bonds and coupon bonds. Under what conditions will a coupon bond sell at a p

Compute the present value of an annuity of 880 per year

Compute the present value of an annuity of $ 880 per year for 16 years, given a discount rate of 6 percent per annum. As

Compute the present value of an 1150 payment made in ten

Compute the present value of an $1,150 payment made in ten years when the discount rate is 12 percent. (Do not round int

Compute the present value of an annuity of 699 per year

Compute the present value of an annuity of $ 699 per year for 19 years, given a discount rate of 6 percent per annum. As