Development and validation of a TRNSYS type to simulate heat pipe heat exchangers in transient applications of waste heat recovery

Daniel Brough,Bertrand Delpech,João Ramos,Hussam Jouhara

doi:10.1016/j.ijft.2020.100056

Daniel Brough, Bertrand Delpech + Show 2 more

Open Access

https://doi.org/10.1016/j.ijft.2020.100056

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Abstract

Heat pipe heat exchangers (HPHEs) are being more frequently used in energy intensive industries as a method of low-grade waste heat recovery. Prior to the installation of a HPHE, the effect of the heat exchanger within the system requires modelling to simulate the overall impact. From this, potential savings and emission reductions can be determined, and the utilisation of the waste heat can be optimised. One such simulation software is TRNSYS. Currently available heat exchanger simulation components in TRNSYS use averaged values such as a constant effectiveness, constant heat transfer coefficient or conductance for the inputs, which are fixed during the entire simulation. These predictions are useful in a steady-state controlled temperature environment such as a heat treatment facility, but not optimal for the majority of energy recovery applications which operate with fluctuating conditions. A transient TRNSYS HPHE component has been developed using the Effectiveness-Number of Transfer Units (ɛ-NTU) method and validated against experimental results. The model predicts outlet temperatures and energy recovery well within an accuracy of 15% and an average of 4.4% error when compared to existing experimental results, which is acceptable for engineering applications.

Highlights

Energy is a central topic of conversation of many developed nations, the overreliance on fossil fuels for energy production
The current zeitgeist is that of a green, carbon-neutral planet which pushes for more sustainable sources of energy, either from harnessing renewable energies but by improving the heat recovery of existing systems
This paper provides a literature review, outlines previous simulations conducted, and shows how an improved simulation methodology has been developed using TRNSYS software to simulate a Heat pipe heat exchangers (HPHEs)’s performance transiently by creating a dedicated HPHE component, which provides accurate predictions on outlet temperatures and energy recovery

Summary

Introduction

Energy is a central topic of conversation of many developed nations, the overreliance on fossil fuels for energy production. Global energy consumption keeps increasing as the world population and the needs of its people increase, but its source may be shifting. At the 2019 United Nations Climate Change Summit, it was announced that countries around the world should reduce emissions by 45% by 2030 on the way to net zero carbon emissions by 2050 [2]. This is a follow up to the 2016 Paris Agreement [3], and has been reinforced by European Union (EU) 2030 energy targets [4], which aim to reduce greenhouse gas emissions to 80-95% below 1990 levels by 2050. Further information on European and UK regulatory frameworks and policies on energy efficiency, in industry, are provided within Ref. [5]

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