Q. Multipass heat exchangers are used

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Q. A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case,

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Q. Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m² .°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the

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Q. Viscosity of gases __________ with increase in temperature.

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Q. What is the emissivity of a black body ?

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Q. Steam is routed through the tube in case of a __________ evaporator.

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Q. Dropwise condensation of steam on cooling surface is promoted

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Q. Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is

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Q. The average heat transfer co-efficient over the entire length of the plate (ha) and the local heat transfer co-efficient (hL), in case of heat transfer over a flat plate in lminar zone is related as

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Q. Maximum heat transfer rate is achieved in __________ flow.

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Q. Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is __________ law.

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Q. Three material A, B and C of equal thick-nes and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of __________ °C.

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Q. The unit of conductance in SI unit is

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Q. In a shell and tube heat exchanger, square pitch compared to triangular pitch

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Q. Which of the following has maximum thermal conductivity ?

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Q. A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of materialA is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is __________ °C.

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Q. The film co-efficient between condensing vapour and metal wall increases with

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Q. A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of

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Q. Heat sensitive materials can be concentrated in an evaporator employing

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Q. A concentric double pipe heat exchanger as compared to the shell and tube heat exchanger for the same heat load requires

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