Boiling Flows in Small and Microchannels (BONSAI): From Fundamentals to Design
Lead Research Organisation:
Brunel University London
Department Name: Mechanical and Aerospace Engineering
Abstract
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Organisations
- Brunel University London (Lead Research Organisation)
- CalGavin (Collaboration)
- Thermacore Europe (Collaboration)
- Oxford nanoSystems Ltd (Collaboration)
- TMD Technologies Limited (Collaboration)
- HiETA Technologies Limited (Collaboration)
- Alfa Laval AB (Collaboration)
- European Organization for Nuclear Research (CERN) (Collaboration)
Publications
Al-Zaidi A
(2021)
Effect of aspect ratio on flow boiling characteristics in microchannels
in International Journal of Heat and Mass Transfer
Al-Zaidi A
(2022)
Flow boiling in copper and aluminium microchannels
in International Journal of Heat and Mass Transfer
Ali H. Al-Zaidi
(2022)
Flow boiling in copper and aluminium microchannels
Ali H. Al-Zaidi
(2022)
Flow boiling in copper and aluminium microchannels
Lee V
(2023)
Influence of system pressure on flow boiling in microchannels
in International Journal of Heat and Mass Transfer
Widgington J
(2022)
Review on Flow Boiling Patterns in Microchannels
Widgington J.J.
(2022)
Review on flow boiling patterns in microchannels
| Description | The effect of material used in micro-scale heat sinks was examined in this work. The flow patterns, heat transfer rates and pressure drop in heat sinks made of aluminum and copper were examined. It was concluded that aluminium heat sinks offer a comparative performance to copper heat sinks. Therefore designers have a choice and and in certain cases aluminium can be use as it is lighter and cheaper for thermal management systems. It was also verified that single passage microgap heat sinks can offer lower pressure drop and pressure fluctuations compared to multi-microchannel heat sinks. However, their critical heat flux is lower compared to the multi-microchannel heat sinks and this limit must be considered in design applications. |
| Exploitation Route | The findings of this work can be used by designers of thermal management systems for high heat flux devices used in, for example, the electronics, computer and IT industry, small scale refrigeration systems, insulated gate bipolar transistors, lasers, photovoltaics and fuel cells. |
| Sectors | Aerospace Defence and Marine Chemicals Electronics Energy Environment Transport |
| Description | The choice of material in microscale heat sinks used to cool high heat flux devices is one of the design choices engineers need to make. In this work we studied experimentally flow boiling patterns, heat transfer rates and pressure drop in heat sinks made of aluminium and copper. The prevailing flow patterns were similar in both heat sinks. The heat transfer coefficient in the aluminium heat sink was 12% (average value) higher than that found in the copper heat sink. The measured pressure drop in the aluminium heat sink was 28% (average value) higher compared to the copper heat sink. However, the additional pumping power required to move the fluid through the micro-scale heat exchanger in a practical thermal management system is small compared to the entire system for this factor to be significant. Therefore, the results of the present study indicate that aluminium heat sinks can offer comparable thermal performance to that of copper heat sinks and can also be recommended for cooling high heat flux systems. A second choice available to designers is the use of single passage microgap heat sinks as compared to multi-channel micro heat sinks. We compared the performance of these two designs for the same base (heat transfer) area. The two-phase pressure drop and pressure fluctuations, in the microgap were lower than that reported in the multi-channel heat sink. However, the lower possible critical heat flux for the microgap and the higher substrate temperatures for a given load compared to the multi-channel micro heat sink, place a lower limitation on the range of possible heat fluxes to be dissipated and this must be considered in the design of thermal management systems. In addition, we are currently examining the performance of a micro-pin fin heat exchanger and hope to make comparative recommendations (microchannels, micro-pin gin and microgap) for industrial design. We are currently preparing a Knowledge Transfer Partnership application for use of these designs in the cooling of fast-charging electric vehicle charging stations. |
| First Year Of Impact | 2024 |
| Sector | Aerospace, Defence and Marine,Electronics,Energy,Environment,Transport |
| Impact Types | Societal |
| Description | Alfa Laval - Heat Exchanger Manufacturer |
| Organisation | Alfa Laval AB |
| Country | Sweden |
| Sector | Private |
| PI Contribution | Too early to say yet |
| Collaborator Contribution | Too early to say yet |
| Impact | Too early to say yet |
| Start Year | 2019 |
| Description | CALGAVIN |
| Organisation | CalGavin |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Too early to say |
| Collaborator Contribution | Too early to say |
| Impact | To early to say |
| Start Year | 2019 |
| Description | CERN |
| Organisation | European Organization for Nuclear Research (CERN) |
| Country | Switzerland |
| Sector | Academic/University |
| PI Contribution | Too early in the project |
| Collaborator Contribution | Too early in the project |
| Impact | Too early in the project |
| Start Year | 2021 |
| Description | HiETA Technologies Ltd |
| Organisation | HiETA Technologies Limited |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Too early in the project |
| Collaborator Contribution | Too early in the project |
| Impact | Too early in the project |
| Start Year | 2021 |
| Description | Oxford nanosystems |
| Organisation | Oxford nanoSystems Ltd |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | To provide accurate data on the effect of coatings produced by Oxford nanosystems on heat transfer rates. This will enable the company to improve marketability of their coating technique for the heat exchanger industry. |
| Collaborator Contribution | To provide coating materials plus time to carry out coating processes. Attend meetings (CEO plus scientific officer) |
| Impact | Too early to estimate from this particular project. Oxford nanosystems benefitted from our collaboration through previous work funded consultancy projects and by Innovate UK. |
| Start Year | 2013 |
| Description | TMD Technologies Ltd |
| Organisation | TMD Technologies Limited |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Too early to say |
| Collaborator Contribution | Too early to say |
| Impact | Too early to say |
| Start Year | 2019 |
| Description | Thermocore Europe Ltd |
| Organisation | Thermacore Europe |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | To provide data on heat transfer with mixtures in microscale heat exchangers as they become available. |
| Collaborator Contribution | Advice on practical design/applications/market possibilities of flow boiling in microchannels |
| Impact | Design of a practical thermal management system for high heat flux devices. This collaboration is still active and Thermacore is partner to a new EPSRC grant. They also worked with Brunel and Oxford nanosystems (OnS) on heat pipes funded by Innovate UK. |
| Start Year | 2006 |