Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Building Services Engineering | en_US |
| dc.creator | Yao, Ting | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/5759 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | - |
| dc.rights | All rights reserved | en_US |
| dc.title | Investigation on the defrosting characteristics of an air-to-air heat pump under different operation conditions | en_US |
| dcterms.abstract | Frosting is a common phenomenon for air-to-air heat pumps working in winter. It affects the efficiency and capacity of the air-to-air heat pump significantly. Although previous research focused on the performance and characteristics of air-source system during defrosting process, few studies were concerned with the effects caused by compressor operation and EEV regulation. In this study, the influence caused by difference in operation of compressor and EEV regulation is considered. Experiments were carried out with three operating conditions: 1) Normal defrosting condition: the speed of compressor was 3000r/min, and the EEV was fully open throughout the defrosting process without degree of superheat regulated. 2) Condition with different speed of compressor: the speed of compressor was set to 2700r/min, 2400r/min and 2100r/min during defrosting process. 3) EEV regulation according to the degree ofsuperheat condition: at the initial of defrosting process, degree of superheat was set to be 5℃, and then the opening of EEV was regulated accordingly. The performances of system with different operation conditions were analyzed and the experimental results of the three conditions were compared. The experimental results indicated that decreasing the speed of compressor could help to system avoid melted frost vaporized. EEV regulation according to degree of superheat could short defrosting time and improve defrosting efficiency. Both these measures can be adopted by operators for efficient air source system defrosting. | en_US |
| dcterms.extent | x, 77 leaves : ill. ; 31 cm. | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2010 | en_US |
| dcterms.educationalLevel | All Master | en_US |
| dcterms.educationalLevel | M.Eng. | en_US |
| dcterms.LCSH | Hong Kong Polytechnic University -- Dissertations | en_US |
| dcterms.LCSH | Heat pumps -- Evaluation. | en_US |
| dcterms.LCSH | Thawing | en_US |
| dcterms.accessRights | restricted access | en_US |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b23563874.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 5.26 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/200/5759