What is it about?

This article explores the numerical analysis of innovative heat exchanger to recover the heat energy from the diesel engines exhaust. The theoretical design and computational fluid dynamics(CFD) simulation of the Protracted Finned Counter Flow Heat Exchanger (PFCHE) was conducted in order to obtain an optimized design for fin protrusions. In this investigation, heat exchanger’s geometric parameters such as fin number and protrusions height have been varied and their subsequent effect on thermal effectiveness was compared. The results of various fin configurations were post-processed and compared in order to obtain better heat transfer rate from the exhaust gases. The contours of temperature distribution, pressure distribution and velocity distribution of exhaust gas with heat exchanger fins and inner pipe surfaces are discussed in detail for different cases of heat exchangers. From the numerical simulation, the PFCHE protrusion fin of 30 mm height revealed the maximum heat recovery rate and exhaust gas temperature reduction rate in comparison with the base heat exchanger model without fins. The simulation result also confirms that the PFCHE with 12 fins of 30mm height is the finest configuration to enhances heat recovery from the diesel engine exhaust gas.

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Why is it important?

Diesel engines are extensively used in small scale electrical power generation and automobiles due to their durability, maximum thermal efficiency and easy maintenance. In internal combustion engines (ICEs), about 30– 45% of fuel energy is converted into work output whereas the remaining fuel energy is being wasted mainly through exhaust gas, exhaust gas recirculation (EGR), and heat losses[1] (Hatami et al., 2014). About 40% of the heat energy gets wasted in exhaust gas whereas the remaining amount of fuel energy goes unused in cooling system as well as during friction losses[2,3] (Ravi et al., 2018, Venkateswarlu, et al., 2018)

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The flow, energy and turbulence equations were solved over the discretized flow domain of the heat exchanger. All the equations were converged and the convergence criteria for flow and turbulence equations were set to be 0.001 and the energy was solved up to 10E-07. The results for all the cases along with a baseline configuration without fins were post processed and consolidated. The results for all the cases along with a baseline configuration without fins were post processed and consolidated. To compare the results, a conventional counter flow heat exchanger without fin and PFCHE with 12-finned configurations were considered. All the contours show the CFD results comparison of conventional heat exchanger (CHE) without fins and various finned design configuration of heat exchanger with different protrusion height of PFCHE.

Rajesh Ravi
Universite Internationale de Rabat

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This page is a summary of: CFD analysis of innovative protracted finned counter flow heat exchanger for diesel engine exhaust waste heat recovery, January 2021, American Institute of Physics,
DOI: 10.1063/5.0036457.
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