Analysis of a Heat Exchanger for a Cogeneration Unit Using Computational Fluid Dynamics

2017 ◽  
Author(s):  
Roman Gášpár ◽  
Stanislav Souček
Keyword(s):  
Heat Exchanger ◽  
Flue Gas ◽  
Waste Heat ◽  
Ideal Gas ◽  
Total Efficiency ◽  
Tube Heat Exchanger ◽  
Unit System ◽  
Exhaust Heat ◽  
Shell And Tube ◽  
Extensive Computation

A cogeneration unit is a device for the production of electricity and heat. Waste heat is used in the cogeneration (Combine Heat and Power or CHP) process. This process increases the efficiency of the whole cogeneration unit system. One of the most important parts of a cogeneration unit is the exhaust heat exchanger, where waste heat is recovered. The objective of this applied research is to examine the properties of a shell-and-tube heat exchanger for a CHP unit of up to 200 kW manufactured by TEDOM a.s. The computations presented in this article are the results of computations where the influence of the composition of flue gas entering the computation in comparison with measured quantities were examined. The article contains a comparison of the influence of the flue gas, represented by CO2, N2 and air as an ideal gas. The results include an analysis of the character of the flow in the heat exchanger, especially in the input volume of the flue gas, where, apart from the influence of the flue gas properties, the influence of the construction on the flue gas mass flow rate distribution into the tubes was also examined. The advantage of this extensive computation lies in the possibility of a detailed analysis of particular parts of the heat exchanger as well as the possibility of detecting potential construction imperfections, which could negatively influence heat transfer and hence the total efficiency of the heat exchanger and the CHP unit.

scholarly journals Thermal-Hydraulic Studies on the Shell-and-Tube Heat Exchanger with Minijets

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3276 ◽  
Author(s):  
Jan Wajs ◽  
Michał Bajor ◽  
Dariusz Mikielewicz
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Waste Heat ◽  
Experimental Studies ◽  
Convection Heat Transfer ◽  
Test Facility ◽  
Experimental Investigations ◽  
Transfer Coefficients ◽  
Tube Heat Exchanger ◽  
Shell And Tube

In this paper a patented design of a heat exchanger with minijets, with a cylindrical construction is presented. It is followed by the results of its systematic experimental investigations in the single-phase convection heat transfer mode. Based on these results, validation of selected correlations (coming from the literature) describing the Nusselt number was carried out. An assessment of the heat exchange intensification level in the described heat exchanger was done through the comparison with a shell-and-tube exchanger of a classical design. The thermal-hydraulic characteristics of both units were the subjects of comparison. They were constructed for the identical thermal conditions, i.e., volumetric flow rates of the working media and the media temperatures at the inlets to the heat exchanger. The experimental studies of both heat exchangers were conducted on the same test facility. An increase in the heat transfer coefficients values for the minijets heat exchanger was observed in comparison with the reference one, whereas the generated minijets caused greater hydraulic resistance. Experimentally confirmed intensification of heat transfer on the air side, makes the proposed minijets heat exchanger application more attractive, for the waste heat utilization systems from gas sources.

Heat Storage and Release Characteristics of Heat Storage Double Shell and Tube Heat Exchanger with Waste Heat Water Temperature

2018 ◽  
Vol 30 (10) ◽  
pp. 462-469
Author(s):  
Geunmyeun Jeong ◽  
Donghyun Kim ◽  
Donggyu Lee ◽  
Dong-Yeol Chung ◽  
Jong-Hyeon Peck ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Water Temperature ◽  
Heat Storage ◽  
Waste Heat ◽  
Tube Heat Exchanger ◽  
Shell And Tube

Exhaust Heat Recovery Unit Equipped With Nanofluid and Helical Tapes, a Solution for Cleaner Energy Production

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
M. Sheikholeslami ◽  
A. Arabkoohsar ◽  
M. Jafaryar
Keyword(s):  
Nusselt Number ◽  
Heat Exchanger ◽  
Environmental Impacts ◽  
Flue Gas ◽  
Heat Recovery ◽  
Internal Combustion Engines ◽  
Waste Heat ◽  
Physical Parameters ◽  
Twisted Tape ◽  
Exhaust Heat

Abstract In internal combustion engines (ICE), a major part of the generated energy via burning the fuel is wasted. The cooling fluid controlling the temperature, the reclaimed hot gases for reducing the environmental impacts, and the hot combustion productions leaving the engine from the exhaust are the main origins of energy waste in such a machine. Waste heat recovery and flue gas condensation are the methods by which the overall efficiency of a thermal engine is enhanced, and its environmental impacts are mitigated. In this paper, the utilization of the exhaust waste energy of ICE by using a heat exchanger with nanofluid and helical tape, in order to augment the thermal performance of the engine and reduce its environmental impact, is investigated numerically. In this heat exchanger, the flue gas of the engine at high temperature and H2O-CuO nanofluid are considered as the primary and secondary working fluids, and the twisted tape makes the flow further disturbed so that a larger overall heat transfer coefficient is obtained. The finite volume method has been applied to scrutinize the impacts of Reynolds number as well as the twisting-tape turns number on the operation and performance of the tube. As such, suitable correlations for the prediction of some of the thermos-physical parameters of the problem (such as Nusselt number and Darcy factor) are extracted regarding the obtained data. The results of the study reveal that Nusselt number is higher for larger numbers of the tape turn and higher Reynolds numbers, while a lower friction factor is achieved as the number of the turns is reduced.

MODELING AND SIMULATION OF A SHELL AND TUBE HEAT EXCHANGER USED FOR REDUCING FLUE GAS TEMPERATURE FOR MICROALGAE MITIGATION

2017 ◽  
Author(s):  
Johana Guadalupe Blanco Martinez ◽  
Leonardo Cavalheiro Martinez ◽  
Iago Costa ◽  
Luiz Rigatti ◽  
Yago Kovara ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Modeling And Simulation ◽  
Flue Gas ◽  
Gas Temperature ◽  
Tube Heat Exchanger ◽  
Shell And Tube

Modelling of Shell and Tube Transport Membrane Condenser Heat Exchangers in Low Grade Waste Heat and Water Recovery Applications

2016 ◽  
Author(s):  
Soheil Soleimanikutanaei ◽  
Esmaiil Ghasemisahebi ◽  
Cheng-Xian Lin ◽  
Dexin Wang
Keyword(s):  
Flue Gas ◽  
Heat Exchangers ◽  
Waste Heat ◽  
Pure Water ◽  
Separation Mechanism ◽  
Low Grade ◽  
Water Recovery ◽  
Condensation Rate ◽  
Tube Heat Exchanger ◽  
Shell And Tube

In this study Transport Membrane Condenser (TMC), a new waste heat and water recovery technology based on a nanoporous ceramic membrane vapor separation mechanism has been studied for waste heat and water recovery in power plant application. TMC is able to extract condensate pure water from the flue gas in the presence of other non-condensable gases (i.e. CO2, O2 and N2). The effects of mass flow rate of flue gas and water vapor content of flow on the heat transfer and condensation rate of a TMC shell and tube heat exchanger have been studied numerically. A single phase multi-component model is used to assess the capability of single stage TMC heat exchangers in terms of waste heat and water recovery at various inlet conditions. Numerical simulation has been performed using ANSYS-FLUENT software and the condensation rate model has been implemented applying User Define Function.

scholarly journals Theoretical and Experimental Analysis of Waste Heat Recovery Effectiveness of a Diesel Engine

2019 ◽  
pp. 1-17
Author(s):  
A. Adeyanju Anthony ◽  
K. Manohar
Keyword(s):  
Heat Exchanger ◽  
Diesel Engine ◽  
Flow Rate ◽  
Waste Heat ◽  
Volumetric Flow Rate ◽  
Rankine Cycle ◽  
Exhaust Gas ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
Volumetric Flowrate

The study utilized the exhaust gas from a diesel engine to preheat water in the constructed shell and tube heat exchanger. The theoretical analysis of the heat exchanger was carried out using the Log Mean Temperature Difference (LMTD) method. The Volumetric flowrate of the water was manipulated using a valve and the resulting output temperature of water leaving the heat exchanger was recorded. Experimentation was carried out to determine the effects of volumetric flow rate on the output temperature and the effectiveness of the heat exchanger. After the test and data analysis, it was discovered that that at flow rate of 3.0 Liter per minute (LPM) the effectiveness of the heat exchanger was peak at 43.34%. The volumetric flow rate of water is inversely proportional to the output temperature of water and it was also established that the effectiveness of the heat exchanger depends on output temperature of and the mass flow rate of the water. Also it was proven that by preheating water before it enters the boiler of the Rankine cycle the efficiency of the cycle increases.

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