What is the thermal conductivity of a perfect heat insulator ?
What is the thermal conductivity of a perfect heat insulator ?
A. Zero
B. One
C. ∞
D. Between 0 and ∞
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In a parallel flow heat exchanger, if the outlet temperature of hot and cold fluids are the same, then the log mean temperature difference (LMTD) is_________________?
In a parallel flow heat exchanger, if the outlet temperature of hot and cold fluids are the same, then the log mean temperature difference (LMTD) is_________________?A. Minimum
B. Maximum
C. Zero
D. Infinity1 BTU/hr.ft.°F is equal to _____________ kcal/hr. m.°C?
1 BTU/hr.ft.°F is equal to _____________ kcal/hr. m.°C?A. 1.49
B. 1
C. 4.88
D. None of theseThree materials A, B and C of equal thickness 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?
Three materials A, B and C of equal thickness 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?A. 40
B. 95
C. 70
D. 50Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is________________?
Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is________________?A. 0.1
B. > 1
C. < 1
D. 1In forced convection, the Nusselt number is a function of ____________________?
In forced convection, the Nusselt number is a function of ____________________?A. Re and Pr
B. Re and Gr
C. Pr and Gr
D. Re and ScThe film co-efficient between condensing vapour and metal wall increases with _____________________?
The film co-efficient between condensing vapour and metal wall increases with _____________________?A. Increasing temperature of the vapour
B. Decreasing temperature of the vapour
C. Increasing viscosity of the film of condensate
D. Increasing temperature drop