Related Questions

The scales form in heat exchanges after a period of operation and provide additional resistance to heat transfer with some heat transfer coefficient . The reciprocal of this scale heat transfer coefficient is called .
A scaling factor
B forming factor
C resisting factor
D fouling factor
Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the
A Surrounding temperature
B Average temperature of the fin
C Temperature of the fin end
D Constant temperature equal to that of the base
Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is
A Finned tube heat exchanger with air inside and steam outside
B Finned tube heat exchanger with air outside and steam inside
C Shell and tube heat exchanger with air inside tubes and steam on shell side
D Shell and tube heat exchanger with air on shell side and steam inside tubes
The concept of overall coefficient of heat transfer is used in heat transfer problems of
A Conduction
B Convection
C Radiation
D Conduction and convection
The concept of overall coefficient of heat transfer is used in case of heat transfer by
A Conduction
B Convection
C Radiation
D Conduction and convection
For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area
A Increases
B Decreases
C Remains constant
D Passes through a maxima
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
A 2
B 20.8
C 20.2
D 20.5
The density of hydrogen is _____ times the density of air.
A 0.07
B 1.5
C 2.5
D 3.5
If Bashar can run around a ground four times in 20 minutes and Rahim can run around the same ground three times in 12 minutes, who can run around that ground more times in an hour, and how many times more can he run around ?
A Bashar, three times more
B Rahim , three times more
C They both go around 12 times
D Bashar, eight times more
A special lottery is to be held to select the student who will live in the only deluxe room in a dormitory . There are 100 seniors, 150 juniors and 200 sophomres who applied. Each senior's junior's name , 2 times; and each sophomres who applied. Each senior's name is placed in the lottery 3 times; each junior's name ,2 times name, 2 times ; and each sphomore's name , 1 time . What is the probability that a senior's name will be chosen?
A 18
B 38
C 48 
D 28

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