Sun, Zhimin
(2019)
A Solid-State Refrigeration Design and Its Analytical Model.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Conventional cooling technology is a very mature technology and had been widely used in industry. However, it has many disadvantages, like environmental pollution and large space to store the device, etc. In order to solve the disadvantages and satisfy current industry requirements, many novel cooling technologies have been explored. Among them, electrocaloric cooling technology attracts a lot of attention due to its outstanding properties, where it has reversible temperature change of a polarizable material with the application of an electric field. Thus, many cooling device designs based on electrocaloric effect have been developed. However, there are two main drawbacks caused by designs to control heat transfer process. One is heat transfer fluid medium loss and the other is moving part requirements (either moving electrocaloric materials or moving fluid medium). The purpose of this thesis is for developing a new and smart heat transfer controlling method. The core design is a composite where electrocaloric layer and substrate layer are bonded together. The composite has temperature change due to electrocaloric effect with application of electric field. In the meantime, it also has converse piezoelectric effect, and thus can bend upward or downward to connect with heat source (or heat sink) for transferring heat. An analytical model is also studied and proposed by considering multi-physical effects in the composite structure, which provides a new way to explore the mechanism of solid-state cooling technology accurately. Our analytical model shows that the temperature change is a combined result from thermal, electric and mechanical field couplings, not just one coupling from electrocaloric effect, which is widely known as Indirect Method derived from Maxwell Equations. Moreover, the model clearly demonstrates that material properties, boundary conditions of the composite, electric field influence cooling performance. The rest of the thesis thoroughly studies various electrocaloric materials, substrate materials, boundary conditions, cooling composite shape. The results show a very promising way to improve cooling performance.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
11 September 2019 |
| Date Type: |
Publication |
| Defense Date: |
1 July 2019 |
| Approval Date: |
11 September 2019 |
| Submission Date: |
8 July 2019 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
102 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Mechanical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Ferroelectrics; solid-state cooling technology; theoretical model; |
| Date Deposited: |
11 Sep 2019 15:21 |
| Last Modified: |
11 Sep 2019 15:21 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/37067 |
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