Concept explainers
A recuperator is a heat exchanger that heats air used ina combustion process by extracting energy from theproducts of combustion. It can be used to increase the efficiency of a gas turbine by increasing the temperature of air entering the combustor.
Consider a system for which the recuperator is a cross-flow heat exchanger with both fluids unmixed andthe flow rates associated with the turbine exhaust and theair are
(a) If the gas and air inlet temperatures are
heat transfer surface area is needed to providean air outlet temperature of
(b) For the prescribed conditions, compute and plotthe air outlet temperature as a function of the heattransfer surface area.
Want to see the full answer?
Check out a sample textbook solutionChapter 11 Solutions
Fundamentals of Heat and Mass Transfer
Additional Engineering Textbook Solutions
Manufacturing Engineering & Technology
Vector Mechanics for Engineers: Statics and Dynamics
Fundamentals Of Thermodynamics
Machine Tool Practices (10th Edition)
Introduction to Heat Transfer
- The purpose of the regenerative heat exchanger is to essentially recycle the heat rejectedin step (B) as heat absorbed in step (D). Show why this works for the case of a general workingfluid with heat capacity, Cv(T).arrow_forwardQ.2. Air enters a steady-flow heat exchanger with a mass flow rate of 2 kg/s as shown in Figure. Determine (a) the rate of heat transfer to the air in the heat exchanger, (b) the power output from the turbine assuming no heat loss, and (c) the velocity at exit from the nozzle. (Cp atr = 1.005 kJ/kg. K) T=600 C T- 12 C V=3 m/s Air Нeat v-3 m/s Exchanger Turbine T= 200 C V - 25 m/s T= 160 C Nozzlearrow_forwardYou as a Biochemical Engineer in an ezyme industries is assigned to handle a counter flow double pipe heat exchanger with A,= 9 m2 which used for cooling a fermentation broth (c, = 3.15 kJ/kg. K) at a rate of 10 kg/s with an inlet temperature of 90°C. The water used as coolant enters the heat exchanger at a rate of 8 kg/s with an inlet temperature of 10°C. The plant data gave the following equation for the overall heat transfer coefficient (in W/m².K): 600 %3D 1 2 • U.8 |m. where m. and m, are the cold and hot stream flow rates in kg/s, respectively.arrow_forward
- Exhaust gases from a power plant are used to preheat air in a cross- flow heat exchanger. The exhaust gases enter the heat exchanger at 450°C and leave at 200°C. The air enters the heat exchanger at 70°C, leaves at 250°C, and has a mass flow rate of 10 kg/s. Assume the properties of the exhaust gases can be approximated by those of air. The overall heat transfer coefficient of the heat exchanger is 154 W/m²K. Calculate the heat exchanger surface area required if the air is unmixed and the exhaust gases are mixed .CPair = 1030 J/kg k Power plant Exhaust in, 450°C Exhaust gases Heat exchanger Air in, 70°C Air out, 250 ℃ Air intakes E Outarrow_forwardTHERMOFLUID A thin-walled double-pipe counter-flow heat exchanger is used to cool oil (C, = 2.20 kJ/kg.°C) from 150 to 40°C at a rate of 2 kg/s by water (c, = 4.18 kJ/kg.°C) that enters at 22°C at a rate of 1.5 kg/s. Determine the rate of heat transfer in the heat exchanger and the exit temperature of water.arrow_forwardAn adiabatic heat exchanger is used to heat cold water át 8 C entering at a rate of 3 kg/s by hot air at 150 C entering also at rate of 3 kg/s. If the exit temperature of hot air is 30 C, the exit temperature of cold water is which of the following: (use constant specific heats evaluated at 300 K). 128.4 C O28.6 C O 31.2 C 36.9 C O 149.7 Carrow_forward
- COMBUSTION ENGINEERING PROBLEM: Cooling water for 507 Horsepower Diesel Engine is to be cooled by using an intermediate cooling heat exchanger as follows. At Counterflow Heat exchanger: Jacket water in --------- 60 °C Jacket water out 38 °C Tower water in 27 °C Tower water out -54 °C To be done: Make the necessary valid assumptions and calculate the flow through heat exchanger for the following quantities: kg 1. Jacket water, in sec kg 2. Tower water, in sec NEAT EXCNANGER DESEL ENGNE from coolingarrow_forward1. A crossflow heat exchanger, one fluid mixed and one unmixed (oil in tubes and steam in shell), is used to heat an oil in the tubes (c = 1.9 kJ/kg°C) from 15°C to 85°C. Steam (5.2 kg/s, c = 1.86 kJ/kg°C) blows across the outside of the tube, enters at 130°C and leaves at 110°C. U. = 275 W/m²K. Calculate A. [10.84 m²]arrow_forwardProblem 2 An air-to-air heat recovery unit uses across-flow exchanger with both fluids unmixed and an airflow rate of 0.5 kg/s on both sides. The hot air enters at 400 °C while the cool air enters at 20 °C. Calculate the exit temperatures for U = 40 W/m². °C and a total exchanger area of 15 m². Take the specific heat of air 1006 J/kg.°c.arrow_forward
- QUESTION 5 The mass flowrate, specific heat, and inlet temperature of the tube-side stream in a double pipe, parallel flow heat exchanger are 3200 kg/h, 2.0 kJ/kg.ºC, and 120 °C respectively. The mass flowrate, specific heat, and inlet temperature of the other stream are 2000 kg/h, 4.2 kJ/kg.°C, and 20 °C respectively. The heat transfer area and overall heat transfer coefficient are 0.5 m² and 2.0 kW/m2.°C, respectively. Discuss your answers by comparing the both methods. i. Propose the best method for the evaluation of the outlet temperatures of both streams in steady operation by considering the LMTD method and the effectiveness-NTU method. ii. Discuss your answers by comparing the both methods.arrow_forwardnote: indicate the diagramarrow_forwardA finned-tube heat exchanger is used as an air-conditioning condenser. During a steady state operation, refrigerant in the tubes remains 2-phase state throughout the heat exchanger at the condensing temperature 67 °C. Air enters the condenser at inlet temperature 28 °C and air mass flow rate is 0.8 kg/s. Refrigerant-side convection thermal resistance and tube wall conduction resistances are negligible. Airside total surface area is 9 m2 and overall surface efficiency is 0.73. Airside average convection coefficient is 65 W/(m2K). The specific heat of air is 1,001 J/(kgK). Determine the heat transfer rate in W.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning