ecthie instrument, you can spray oil painting with ger, a liquid was cooled by f

Question

ecthie instrument, you can spray oil painting with ger, a liquid was cooled by frozen brine(????) with-10?. The flu B Multiple choices (24 points) fluid should be arranged i I. In a double-pipe exchanger, hot flow was cooled from 90? to 60? and the temperature C to 50 C. countercu For countercurrent flow, ?T-=- ?)70 B) 30C ugh a 025*2.5 mm at a turbulent flow. Its coefficient of convection heat transfer is y and physical properties are unchanged, the tube is changed to ? 1942 mm. what is the h? 2. Some liquid is flowing thro C) 10C D) 40 C A) 1059: B) 1496: C) 1585: D)1678. In a horizontal improve the overall heat transfer coefficient. A. Improving the air flow exchanger, stream is used to heat air. The air is in tube-side and the steam is in shell-side. In order to which method is the best one? B. Increasing the flow rate of steanm The emwim ducti Changing the flow direction of air and steam D. Putting the exchanger vertically W/m2 at 300 C : T he emissivity of red brick is 0.93. The emissive power of it should be A) 6112.3 W/m C) 916.8 W/m D) 1000 W/m2 B) 5686 W/m2 The thermal The thermal conductivity of air at atmospheric temperature isThe thermal 62 W/m.C 0.025 W/m.C e thermal conductivity of carbon steel is The thermal conductivity of stainless steel is conductivity of copper is conductivity of water at atmospheric temperature is A) 151 W/m. C B)370 W/m. C 6. Given: The emissive pow emissivity of refractory should be C) 45 W/m. C D) 16 w/m.CE er of refractory(???) is bigger than that of polished copper at T temperature. Then: The C) 1 B) 0.03 A) 0.85 7. The aim of dimensional analysis lies in A) Simplify the experiment and relevance work using the dimensionless groups instead of variables B) Get the exact quantitative relationship between dimensionless g roups Get the exact quantitative relationship between variables Make the results more reliable using the dimensionless groups instead of variables In steady-state, a flat-wall consists of three layers, as shown in figure. Try to compare the heat C) D) resistance Ri and (Ro+Rs) A)R,> (R2tR,) B)R, (R+R) C)R (R2+R) D) Unable to compare

Explanation / Answer

Note: As per regulations only one problem can be solved at a time with it's sub parts. As you have not listed which one to solve i am solving the first problem.

1. The counter-current heat exchangers especially the ones that are employed by using two pipes running parallel to each other with flow of liquids to undergo heat exchange in opposite directions to each other. This results in a loss of heat by the hot liquid and the cold liquid gaining heat for a temperature increase.

Here Delta T is simply the change in temperature for the cases of hot and cold flow which comes out to be 90-60 = 30 and also 50-20 = 30.

Hence the correct answer is (B) 30 C

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