| Author: | Chiu, Ka Hei Kenneth |
| Title: | Study of heat transfer enhancement of phase change materials (PCMs) |
| Advisors: | Lu, Lin (BSE) |
| Degree: | M.Eng. |
| Year: | 2021 |
| Subject: | Paraffin wax Materials -- Thermal properties Energy storage Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Building Services Engineering |
| Pages: | [87] pages : color illustrations |
| Language: | English |
| Abstract: | Energy usage in building keeps increased in worldwide, control on thermal comfort took the major part of it. Energy saving on thermal control in building became a serious concern to both government and public. Apart from reducing energy usage, thermal energy storage had been promoted to achieve energy saving, for example shifting the peak of energy usage for space heating and cooling plants. In this dissertation, paraffin as phase change materials were studied by the means of experimental analysis to exam its ability to perform thermal energy storage. Physical properties of paraffin is measured though experiment. Thermal conductivity in both liquid and solid state was measured though transient hot wire method; latent heat capacity and specific heat capacity were examined by differential scanning calorimeter with calculation; viscosity obtained from viscosity meter. By the data of measured physical properties of paraffin, it is suitable to be material for thermal energy storage by high latent heat capacity. But it is expected the property of low thermal conductivity would result drop of thermal energy storage performance. This event became more critical with the present of liquid state after the paraffin has absorbed enough heat to change its phase. Experiment on heating pure paraffin in a small acrylic chamber has been done to prove the drop of performance in heat absorption. The experiment provide constant heat source to paraffin. Heat energy produced will be absorbed by paraffin and stored in the form of latent heat. Sensible heat gain in paraffin would also occur in this experiment. Enhancement is proposed for facing the problem of drop in performance during the phase change process. Metal is suggested in this study by the property of high thermal conductivity. Heat absorption performance of phase change material with copper rods, copper fins and copper metal foam were tested. Copper metal have high thermal conductivity among metals commonly used in the market. It is also frequency used for heat exchanger. Temperature sensors is adopted to measure change of temperature in different level of chamber, total heat energy gain in chamber can be resulted from calculation of temperature data. Copper enhancement methods improved heat transfer into all paraffin used. Three types of the method have been proved to have significant effect on of improvement on energy absorbed by paraffin. Different level of increase in amount of melted paraffin shows the improvement of performance in the experiment. Moreover, the application of enhancement methods has been discussed in the aspect of economic analysis. Design with copper rods and fins have resulted higher cost effective, percentage of increase in energy absorption by less additional cost on enhancement method. On the other hand, metal foam required high cost for similar improvement result. Price of material has been discussed as part of the economic analysis, copper is suggested to be replaced by aluminum, which has high thermal conductivity with lower price. Based on the property of experiment, the enhancement method is suggested to be applied for the thermal storage in building compartments. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 5723.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 1.65 MB | Adobe PDF | View/Open |
Copyright Undertaking
As a bona fide Library user, I declare that:
- I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
- I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
- I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.
By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.
Please use this identifier to cite or link to this item:
https://theses.lib.polyu.edu.hk/handle/200/11247