GTU BE/B.Tech 2018 Winter Question Papers || Gujarat Technological University
BE - SEMESTER-V (NEW) EXAMINATION — WINTER 2018
Subject Code: 2153613
--- Content provided by FirstRanker.com ---
Subject Name: Basics of Heat Transfer
Date: 16/11/2018
Time: 10:30 AM TO 01:00 PM
Total Marks: 70
Instructions:
--- Content provided by FirstRanker.com ---
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
| Q1 | MARKS |
| (a) Explain mode of heat transfer. | 03 |
| (b) Explain Fourier’s law and Newton’s law of cooling. | 04 |
| (c) Derive an expression for steady state heat conduction through hollow sphere. | 07 |
| Q2 | |
| (a) What do you mean by convection? How do you differentiate between free and force convection? | 03 |
| (b) A hot plate 1m x 1.5m is maintained at 300°C. Air at 20°C blows over the plate. If the convective heat transfer coefficient is 20 W/m2°C, calculate the rate of heat transfer. | 04 |
| (c) Explain extended surface with different types. Derive the expression for heat transfer from infinitely long fin. | 07 |
| OR | |
| (c) A furnace wall is composed of 250 mm of fire bricks, 200 mm of common brick, 50 mm of 85% magnesia and 3 mm of steel plate on outside. If the inside surface temperature is 1800 K and outside surface temperature is 363 K, estimate the temperature between layer and calculate the heat loss. Assure k (for fire brick) =4 W/(m.K), k (for common brick)=2.8 W/(m.K), k (85% magnesia)=0.24 W/(m.K) and k (for steel)=240 W/(m.K). | 07 |
| Q3 | |
| (a) List out various laws of radiation and explain any one in detail. | 03 |
| (b) Write Dittus Boelter equation to compute heat transfer coefficient. Explain all the terms with their SI units | 04 |
| (c) Lubricating oil used in gear box of a 14000 rpm high speed blower is being recycled continuously through a double pipe counter current heat exchanger for cooling. The oil is cooled from 70°C to 40°C at the rate of 1000 kg/h using water entering at 28°C. The water temperature at exit should not exceed 42°C. The specific heat of oil is 2.05 kJ/kg °C and that of water is 4.17 kJ/kg °C. Calculate required rate of flow of water. If the heat exchanger area is 3.0 m2, calculate the overall heat transfer coefficient. | 07 |
| OR | |
| (a) Give the physical significance of : Fourier’s Number, Biot number and Reynolds number | 03 |
| (b) Explain hydrodynamic and thermal boundary layers. | 04 |
| (c) What is critical radius? Why it is necessary? Derive expression of critical radius for Spherical shape. | 07 |
| Q4 | |
| (a) Explain with neat sketch falling film evaporator. | 03 |
| (b) Explain feeding arrangements in multi effect evaporator (any one) | 04 |
| (c) What are different flow arrangements in heat exchanger? Derive the equation for L.M.T.D. in co-current flow heat exchanger. | 07 |
| OR | |
| (a) Explain construction and working of plate heat exchanger with neat sketch. | 03 |
| (b) Explain boiling point elevation and duhring’s rule | 04 |
| (c) Derive the expression for Reynolds analogy. | 07 |
| Q.5 | |
| (a) Elaborate the concept of Black Body and Grey Body. | 03 |
| (b) Explain film wise and drop wise condensation. | 04 |
| (c) Explain shell and tube heat exchanger. | 07 |
| OR | |
| (a) Explain the construction and working of calendria type evaporators | 03 |
| (b) What is evaporation economy? Which are the different method for increase economy? | 04 |
| (c) What is condensation? What are the different factors which affects condensation? | 07 |
--- Content provided by FirstRanker.com ---
This download link is referred from the post: GTU BE/B.Tech 2018 Winter Question Papers || Gujarat Technological University