3D-Printed Heat Exchanger

Abstract (Swedish)

Additiv tillverkning, eller 3D-printing, är på grund av sina många fördelar en ständigt ökande tillverkningsmetod. Designfriheten, det reducerade materialspillet, förkortad tid från ritning till färdig produkt och förmågan att kunna printa rörliga delar gör 3D-printing intressant för många olika användningsområden. Ett användningsområde där relativt lite forskning gjorts men som har ett ökat intresse är värmeväxlare.
Värmeväxlare används idag i oräkneliga applikationer, bland annat i industrin, fordon, datorer, kraftverk etc. Att designa en värmeväxlare är en komplex process där de minsta ändringarna på geometri kan ha stora konsekvenser för prestandan. Värmeöverföringsarea är en av de begränsande faktorerna för värmeöverföring. En möjlighet som designfriheten additiv tillverkning medför är att man kan addera till arean genom komplexa geometrier.
En Shell-and-Tube värmeväxlare ämnad för 3D-printing designades med CAD. Först gjordes beräkningar som jämförde den areaökning som kunde erhållas jämfört med en konventionell liknande värmeväxlare. De båda värmeväxlarna jämfördes även med CFD analys för att utvärdera möjligheterna för ökad värmeöverföring. Även parametrar som tryck, temperatur och flöde analyserades. Enligt teorin ska ökad area innebära mer värmeöverföring men från resultaten av CFD kan inga generella slutsatser dras. Inga direkta temperaturskillnader syntes vid jämförelsen av de båda värmeväxlarna.
Arbetet var även en studie i hur väl moderna 3D-printrar ämnade för metallkomponenter kan hantera komplexa ytor och smala passager. Shell-and-Tube värmeväxlaren designades för att minimera mängden supportmaterial och hur väl pulver kunde avlägsnas undersöktes också.

Abstract

Additive manufacturing, or 3D-printing, is due to its many advantages an increasingly used form of manufacturing. The design freedom, reduced material waste, shortened process from drawing to finished product, and the ability to print moving parts make it extremely interesting for many applications. One application where not much research has been done, but there is an increasing interest, is the field of heat exchangers.
Heat exchangers are used in countless applications such as industry, vehicles, computers, power plants etc. The process of designing a heat exchanger is complex and even the smallest geometric changes can have a great impact of their performance. Heat transfer area is one of the limiting factors for heat transfer and adding area with complex geometries is made available with the design freedom additive manufacturing brings.
A Shell-and-Tube heat exchanger was designed using CAD, for the purpose of 3D-printing. Calculations were first made to determine the area increase compared to a similar conventional heat exchanger. The two heat exchangers were also compared, through CFD simulations to determine the possibilities for increased heat transfer. Parameters such as pressure drop, temperature and fluid flow were analyzed. From theory, adding area will increase heat transfer, but from the results of the CFD analysis no such conclusion can be drawn. No real temperature difference could be seen when comparing complex to conventional heat exchangers.
The work was also a study in how well modern 3D-printers, for metal components, handle complex surfaces and narrow tube passages. The Shell-and-Tube was designed to minimize support material but powder removal also a factor that was investigated.

Popular Abstract

Radiators for keeping warm in winter, AC for those hot summer days, that smartphone that keeps getting too hot. All of these and many more applications need heat exchangers. The most efficient heat exchanger known is the human lung. With 3D printing the complexity of a lung might be possible to copy.
The technology to increase or decrease temperature is seen all around us and there are numerous ways to accomplish this. Even if conventional heat exchangers can be made quite efficient, they are still nowhere near as efficient as those designed through millennia of evolution. This work was centred around designing and printing a heat exchanger that would not be possible to manufacture with conventional techniques.
The human lung is around 20 times as efficient as common heat exchangers. Through the rapidly developing technology of 3D-printing there is a possibility to get closer to the complex designs found in nature. This would not only mean a better heat exchange but also be very beneficial for energy use, which with climate change is of huge importance.
The different forms of heat transfer come in three. Radiation is the heat the sun produces to warm our planet. Conduction is the heat you feel when you touch a hot pan that has stood on the stove. Convection is the heat transfer for cooling your hand in running water after it was burned on the pot. All these types of heat transfer happen in a heat exchanger, but the radiation is very small in the big picture. As there are many things happening at once, the ability to give numbers of what is happening is difficult. To help engineers there are sophisticated software which can help in doing Computational Fluid Dynamics (CFD) calculations. This software is used to simulate the flow, temperature and pressure in the heat exchanger of choice.
In this thesis it is shown that the design of an average heat exchanger may be changed through the help of 3D-printing, creating a more efficient heat exchanger. The important things to think about when creating with 3D is that as little as possible post processing should be needed.
3D printing technology uses a metal or plastic powder in a powder bed that with a 3D model as drawing uses a high focused laser to melt the powder and this way builds the part. The residual powder needs to be removed after printing with post processing. Through clever design this post processing can be reduced to a minimum. It is believed that this knowledge can help push research forward in the field of heat exchangers, creating the heat exchangers of tomorrow. It is shown that previously impossible designs quite easily can be done with 3D printing.
The technology of 3D printing has huge potential of creating a smarter and better heat exchanger. If the heat exchanger can be made smaller but with the same output this could have big impacts on cost and more importantly it is more sustainable. Less energy needed to have the same effects means less emissions. It could be used in everything from industry and refineries to home applications such as home brewers wanting a better way to cool their latest batch of beer.

• author: Ljungman, Johannes
• supervisor: Martin Andersson
• organization: Innovation
• course: MMKM05 20191
• year: 2019
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Additive Manufacturing, Heat Transfer, Heat Exchanger, Computational Fluid Dynamics, Computer Aided Design
• language: English
• id: 8988071
• date added to LUP: 2019-06-26 08:05:32
• date last changed: 2019-06-26 08:05:32