CFD and Experimental Study of Heat Exchangers for Transient Heating Application
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Global warming is a problem to the environment and a threat to the lifestyle people have today. The average temperature around the world is increasing and it is mainly because the increased amount of greenhouse gases in the atmosphere. Emissions of greenhouse gases are mainly caused by using fossil fuels to create electricity. The problem investigated in this thesis study originates from a company that intends to create electricity by means of renewable energy sources. The energy is transferred from thermal energy to kinetic energy and from the kinetic energy, electricity is generated with a generator.
The company’s system is operating with standard components with insufficient efficiency. Advancement to the next level is depending on finding a solution to improve the performance of their main component in the system. The main component is a brazed plate heat exchanger that is used to transfer heat from one medium to another. Process cycle is strongly dependent on the time it takes to heat and cool the media inside the heat exchanger. The objective of this thesis is to analyze the transient behavior of heat exchangers and with this information compare two construction types to show what type is more appropriate to use inside the system.
Evaluation is made experimentally and with means of Computational-Fluid-Dynamics (CFD) where two CFD-tools are evaluated. To create a reference case to compare results against, the model of the heat exchanger used today is created as a reference model. The reference model is compared to experimental measurement to show the validity of the simulation set-up. From design guidelines received from the company, an alternative construction type is chosen and compared towards the plate heat exchanger. The tube-fin heat exchanger with continuous plates across a bundle of tubes is parametrically studied. The best-determined concept is compared to the plate heat exchanger.
Evaluation of the CFD-tools shows that two identical geometries with identical set-up can give a difference in the results based on the tool chosen for the simulation. It is shown by results that the transient behavior of heat exchangers in a CFD-simulation have a general agreement with experimental results. The agreement depends on the control of the experimental set-up. The comparison between the best concept and the reference model shows that the difference in average gas temperature during 5 seconds of transient heating is at most 1.1 degrees. Construction types is therefore also evaluated on material-cost, thermal mass and guidance from heat exchanger handbooks.
The results indicate that the tube-fin heat exchanger is more suitable to use in the system. It reduces material, reduces environmental impact and matches the performance of the industrial plate heat exchanger.
Place, publisher, year, edition, pages
2016. , 78 p.
Plate heat exchanger, tube-fin heat exchanger, computational fluid dynamics, heat transfer, heat exchangers, experiments, transient heating
Energy Engineering Metallurgy and Metallic Materials
IdentifiersURN: urn:nbn:se:hj:diva-30998ISRN: JU-JTH-PRU-2-20160046OAI: oai:DiVA.org:hj-30998DiVA: diva2:945406
Subject / course
JTH, Product Development
Belov, Ilia, Phd with major in Physics and Mathematics
Salomonsson, Kent, Teknologie doktor