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A heat exchanger with heat transfer surface area A and overall heat transfer coefficient U handles two fluids of heat capacities C<sub>max</sub> and C<sub>min</sub>. The number of transfer units (NTU) used in the analysis of heat exchanger is specified as

Correct Answer: AU/C<sub>min</sub>
A heat exchanger with heat transfer surface area A and overall heat transfer coefficient U handles two fluids of heat capacities Cmax and Cmin. The number of transfer units (NTU) used in the analysis of heat exchanger is specified as AU/Cmin.

Water (specific heat = 4 k J/kg K) enters a cross flow exchanger (both fluids unmixed) at 15 degree Celsius and flows at the rate of 7.5 kg/s. It cools air (C P = 1 k J/kg K) flowing at the rate of 10 kg/s from an inlet temperature of 120 degree Celsius. For an overall heat transfer coefficient of 780 k J/m2 hr degree and the surface area is 240 m2, determine the NTU

In a surface condenser, the water flowing through a series of tubes at the rate of 200 kg/hr is heated from 15 degree Celsius to 75 degree Celsius. The steam condenses on the outside surface of tubes at atmospheric pressure and the overall heat transfer coefficient is estimated at 860 k J/m2 hr degree. Find the number of transfer units of the heat exchanger. At the condensing pressure, stream has saturation temperature 0f 100 degree Celsius and the latent heat of vaporization is 2160 k J/kg. Further, the steam is initially just saturated and the condensate leaves the exchanger without sub-cooling i.e. only latent heat of condensing steam is transferred to water. Take specific heat of water as 4 k J/kg K

A designer chooses the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal. A hot fluid enters the counter flow heat exchanger at 100°C and leaves at 60°C. A cold fluid enters the heat exchanger at 40°C. The mean temperature difference between the two fluids is

Some pins are needles. Some needles are handles. Some handles are locks. Some locks are keys. Conclusions: I. Some keys are handles II.Some handles are pins III. Some pins are keys

Forced air flows over a convection heat exchanger in a room heater, resulting in a convective heat transfer coefficient 1.136 k W/m2 K. The surface temperature of heat exchanger may be considered constant at 65 degree Celsius, and the air is at 20 degree Celsius. Determine the heat exchanger surface area required for 8.8 k W of heating

In a surface condenser, the water flowing through a series of tubes at the rate of 200 kg/hr is heated from 15 degree Celsius to 75 degree Celsius. The steam condenses on the outside surface of tubes at atmospheric pressure and the overall heat transfer coefficient is estimated at 860 k J/m2 hr degree. Find the effectiveness of the heat exchanger. At the condensing pressure, stream has a saturation temperature 0f 100 degree Celsius and the latent heat of vaporization is 2160 k J/kg. Further, the steam is initially just saturated and the condensate leaves the exchanger without sub-cooling i.e. only latent heat of condensing steam is transferred to the water. Take specific heat of water as 4 k J/kg K

Raw material purchased:
1st January, 600 units @ Rs. 12 per unit
12th January, 500 units @ Rs. 14 per unit
21st January, 300 units @ Rs. 13 per unit
Raw material issued for manufacture:
3rd January 300 units
5th January 124 units
15th January 250 units
16th January 300 units
Raw material returned to stores from manufacturing department on 14th January, 50 units. The material is issued on First-in-First out method.
The value of material remaining in store on 21st January will be:

Which of the following statements about Printed circuit heat exchanger are correct? Statement 1: Printed circuit heat exchanger is an example for direct heat exchanger. Statement 2: It has high heat transfer surface area per unit volume of the exchanger.

After being in service for a period of six months, a heat exchanger transforms 10% less heat than it does what new. Determine the effective fouling factor in terms of its clean overall heat transfer coefficient. It may be presumed that the heat exchanger operates between the same temperature differentials and that there is no change in the effective surface area due to scale build up

A finned surface consists of root or base area of 1m2 and fin surface area of 2m2. The average heat transfer coefficient for finned surface is 20W/m2K effectiveness of fins provided is 0.75. If finned surface with surface with root or base temperature of 50°C is transferring heat to fluid of 30°C, then the rate of heat transfer without using fin is _______