Q. In how many categories heat exchangers are classified on the basis of mechanical design of heat exchanger surface?

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Q. In how many categories heat exchangers are classified on the basis of physical state of heat exchanging fluids?

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Q. Many types of heat exchangers have been developed to meet the widely varying applications. Based upon their

(i) Operating principle
(ii) Arrangement of flow path
(iii) Design

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Q. How many fluids remain at constant temperature during the process of boiling and condensation?

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Q. Identify the correct expression for effectiveness

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Q. In a gas turbine recuperator, the capacity ratio becomes

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Q. In a gas turbine recuperator, the expression for effectiveness for the parallel flow configuration reduces to

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Q. What is the maximum efficiency for parallel flow heat exchanger?

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Q. The curve of effectiveness versus NTU parameters indicates the relationship between

(i) Effectivenes
(ii) NTU MAX
(iii) C MIN/C MAX

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Q. Hot water having specific heat 4200 J/kg K flows through a heat exchanger at the rate of 4 kg/min with an inlet temperature of 100 degree Celsius. A cold fluid having a specific heat 2400 J/kg K flows in at a rate of 8 kg/min and with inlet temperature 20 degree Celsius. Make calculations for maximum possible effectiveness if the fluid flow conforms to parallel flow arrangement

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Q. A counter flow heat exchanger is used to col 2000 kg/hr of oil (c p = 2.5 k J/kg K) from 105 degree Celsius to 30 degree Celsius by the use of water entering at 15 degree Celsius. If the overall heat transfer coefficient is expected to be 1.5 k W/m² K, find out the water flow rate. Presume that the exit temperature of the water is not to exceed 80 degree Celsius

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Q. Assumptions made for calculation of logarithmic mean temperature difference are

(i) Constant overall heat transfer coefficient
(ii) The kinetic and potential energy changes are negligible
(iii) There is no conduction of heat along the tubes of heat exchanger

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Q. A cold fluid (specific heat 2.95 k J/kg K) at 10 kg/min is to be heated from 25 degree Celsius to 55 degree Celsius in a heat exchanger. The task is accomplished by extracting heat from hot water (specific heat 4.186 k J /kg K) available at mass flow rate 5 kg/min and inlet temperature 85 degree Celsius. Identify the type of arrangement of the heat exchanger

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Q. In a food processing plant, a brine solution is heated from – 12 degree Celsius to – 65 degree Celsius in a double pipe parallel flow heat exchanger by water entering at 35 degree Celsius and leaving at 20.5 degree Celsius. Let the rate of flow is 9 kg/min. Estimate the area of heat exchanger for an overall heat transfer coefficient of 860 W/m² K. For water c P = 4.186 * 10³ J/kg K

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Q. Exhaust gases (c P = 1.12 k J/kg K) flowing through a tubular heat exchanger at the rate of 1200 kg/hr are cooled from 400 degree Celsius to 120 degree Celsius. This cooling is affected by water (c P = 4.18 k J/kg K) that enters the system at 10 degree Celsius at the rate of 1500 kg/hr. If the overall heat transfer coefficient is 500 k J/m² hr degree, what heat exchanger area is required to handle the load for parallel flow arrangement?

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Q. A steam condenser is transferring 250 k W of thermal energy at a condensing temperature of 65 degree Celsius. The cooling water enters the condenser at 20 degree Celsius with a flow rate of 7500 kg/hr. Calculate the log mean temperature difference

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Q. For what value of end temperature difference ratio, is the arithmetic mean temperature difference 5% higher than the log-mean temperature difference?

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Q. A company is heating a gas by passing it through a pipe with steam condensing on the outside. What percentage change in length would be needed if it is proposed to triple the heating capacity?

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Q. A steam condenser is transferring 250 k W of thermal energy at a condensing temperature of 65 degree Celsius. The cooling water enters the condenser at 20 degree Celsius with a flow rate of 7500 kg/hr. If overall heat transfer coefficient for the condenser surface is 1250 W/m² K, what surface area is required to handle this load?

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Q. Exhaust gases (c P = 1.12 k J/kg K) flowing through a tubular heat exchanger at the rate of 1200 kg/hr are cooled from 400 degree Celsius to 120 degree Celsius. This cooling is affected by water (c P = 4.18 k J/kg K) that enters the system at 10 degree Celsius at the rate of 1500 kg/hr. If the overall heat transfer coefficient is 500 k J/m² hr degree, what heat exchanger area is required to handle the load for counter flow arrangement?

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