--%>
Assignment Help - homework help

Problem on convection coefficient

An experiment to determine the convection coefficient associated with airflow over the surface of a thick stainless steel casting involves 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 measured the temperatures of 50°C and 40°C in the steel, respectively, 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 between the steel and hot air?

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

In the recurring experiments the duct insulation was eliminated and even though the hot air temperature was similar as before, i.e., 200oC, the surrounding walls temperature dropped to 20oC. As a result the steady state heat flux to the steel casting dropped by 13.3% compared to the first experiment.

c) Supposing similar convection coefficient as the value coputed in part a), what would be the temperatures measured by the thermocouples?

d) Assume that the steel casting were well insulated from each and evry side except for the surface from which the distance to thermocouples is measured. Assuming the same convection coefficient as the value calculated 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 executed in non-insulated duct at T∞ = 100oC and Tsurr = 20oC?

   Related Questions in Chemistry

  • Q : Problem on physical and thermodynamic

    The shells of marine organisms contain calcium carbonate CaCO3, largely in a crystalline form known as calcite. There is a second crystalline form of calcium carbonate known as aragonite. Physical and thermodynamic properties of calcite and aragonite at 298

    		•
  • Q : Normality of solution containing

    Can someone please help me in getting through this problem. Determine the normality of a solution having 4.9 gm H3PO4 dissolved in 500 ml water: (a) 0.3  (b) 1.0  (c) 3.0   (d) 0.1

    		•
  • Q : Procedure to judge that organic

    Describe briefly the procedure to judge that the given organic compound is pure or not?

    		•
  • Q : Molarity of Sodium hydroxide Select the

    Select the right answer of the question. Molarity of 4% NaOH solution is : (a) 0.1M (b) 0.5M (c) 0.01M (d) 0.05M

    		•
  • Q : Problem related to molarity Provide

    Provide solution of this question. Increasing the temperature of an aqueous solution will cause: (a) Decrease in molality (b) Decrease in molarity (c) Decrease in mole fraction (d) Decrease in % w/w

    		•
  • Q : Question based on vapour pressure and

    Benzene and toluene form nearly ideal solutions. At 20°C, the vapour pressure of benzene is 75 torr and that of toluene is 22 torr. The parial vapour pressure of benzene at 20°C for a solution containing 78g of benzene and 46g of toluene in torr is: (a) 50 (b)

    		•
  • Q : Symmetry Elements The symmetry of the

    The symmetry of the molecules can be described in terms of electrons of symmetry and the corresponding symmetry operations.Clearly some molecules, like H2O and CH4, are symmetric. Now w

    		•
  • Q : Show your calculations Superphosphate

    Superphosphate has the formulae: CaH4 (PO4)2H2).  Calculate the percentage of phosphorus in this chemical.  Show your calculations  (around ten lines);  also Work out how to make up a nutrient mixtur

    		•
  • Q : What is laser and explain its working?

    Laser action relies on a non-Boltzmann population inversion formed by the absorption of radiation and vibrational deactivation that forms a long lived excited electronic state. An excited state molecule can move to a lower energy state or return to the

    		•
  • Q : Molarity A solution has volume 200ml

    A solution has volume 200ml and molarity 0.1.if it is diluted 5times then calculate the molarity of reasulying solution and the amount of water added to it.

    		•