JNTU
JNTU B.Tech III PROCESS HEAT TRANSFER Previous Question Paper (May/June - 2019 - R13)
Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit.
Part A
Define thermal conductivity.
Answer
Thermal conductivity is a material property that measures its ability to conduct heat. It is defined as the rate of heat transfer through a unit thickness of a material per unit area per unit temperature difference.
What is heat flux. State the different modes of heat transfer.
Answer
Heat flux is the rate of heat energy transfer per unit area of a surface. The three primary modes of heat transfer are conduction (transfer through stationary matter by physical contact), convection (transfer by the movement of fluids), and radiation (transfer via electromagnetic waves).
What is a heat exchanger.
Answer
Sign in to view the complete answer paper.
What is Fouling of heat exchanger? Explain.
Answer
Sign in to view the complete answer paper.
What is Reynolds number?
Answer
Sign in to view the complete answer paper.
What is the effect of roughness on heat transfer of fluids in pipes.
Answer
Sign in to view the complete answer paper.
What is the significance of Nusselt number.
Answer
Sign in to view the complete answer paper.
Write a note on mechanism of boiling.
Answer
Sign in to view the complete answer paper.
Write the Donohue equation for a multipass exchanger.
Answer
Sign in to view the complete answer paper.
Define boiling point elevation and Duhring’s rule.
Answer
Sign in to view the complete answer paper.
Part B
A flat surface wall is constructed of a 4.5 inch layer of Sil-o-Cel brick, with a thermal conductivity of 0.08 Btu/ft.h.F backed by a 9 inch layer of common brick of conductivity of 0.8 Btu/ft.h.F. The temperature of the inner wall face of the wall is 1400F and that of the outer surface is 170F. What is the heat loss through the wall and What is the temperature of the interface between the two brick layers.
Answer
Sign in to view the complete answer paper.
Derive an expression for heat flow through a series of layer of three flat walled surfaces of varying thickness.
Answer
Sign in to view the complete answer paper.
Derive the equation for steady state heat transfer through a spherical shell of inner radius r1 and outer radius r2.
Answer
Sign in to view the complete answer paper.
An oil storage tank has a 20 mm steel walls covered with 50 mm of fiber glass insulation. If the oil temperature is kept at 150°C, (i) what is the rate of heat loss when the outside temperature is 20°C and the external air coefficient is 20W/m²°C? (ii) How much the heat loss may be reduced by doubling the thickness of the insulation?
Answer
Sign in to view the complete answer paper.
Methyl alcohol flowing in the inner pipe of a double pipe exchanger is cooled with water flowing in the jacket. The inner pipe is made from 1 inch Schedule 40 steel pipe. The thermal conductivity of steel is 26 Btu/ft.h.F. The individual coefficients and fouling factor are given in the table. What is the overall coefficient, based on the outer outside area of the inner pipe?
Answer
Sign in to view the complete answer paper.
With a neat sketch, explain the construction and working principle of a double pipe heat exchanger.
Answer
Sign in to view the complete answer paper.
What is LMTD? Explain the assumptions involved in derivation of LMTD.
Answer
Sign in to view the complete answer paper.
A oil with the characteristics given below in the table is to be heated from 150 to 250°F in a 6.35 mm Schedule 40 pipe 15 ft long. The pipe wall is at 350°F. How much oil can be heated in this pipe, in pounds/hour. What coefficients can be expected.
Answer
Sign in to view the complete answer paper.
What is Prandtl number? What is its significance?
Answer
Sign in to view the complete answer paper.
Explain the analogy between momentum and heat transfer.
Answer
Sign in to view the complete answer paper.
Benzene is boiling at atm. pressure in a kettle–type boiler with horizontal tubes. (i) Estimate the maximum heat flux for a single tube. (ii) Predict the maximum flux for pressures of 0.2 and 5 atm.
Answer
Sign in to view the complete answer paper.
Write a note on “Radiation to absorbing gases”.
Answer
Sign in to view the complete answer paper.
Derive the equation for combined heat transfer by conduction, convection and radiation.
Answer
Sign in to view the complete answer paper.
Discuss about extended surface heat exchangers.
Answer
Sign in to view the complete answer paper.
Describe the methods of feeding in multiple effect evaporation.
Answer
Sign in to view the complete answer paper.