| Author: | Chen, Qingxin |
| Title: | Comparison of the sleeping thermal environment between convection-based system and bed-based heating system powered by air source heat pump technology in winter |
| Advisors: | Deng, Shiming (BSE) |
| Degree: | M.Eng. |
| Year: | 2019 |
| Subject: | Hong Kong Polytechnic University -- Dissertations Heat pumps Dwellings -- Heating and ventilation |
| Department: | Department of Building Services Engineering |
| Pages: | 93 pages : color illustrations |
| Language: | English |
| Abstract: | Sleep is essential for human with basic need and the improvement for physical and psychological health. Thermal environment has a great impact on the quality of human sleep, which people tend to improve their thermal comfort by using heating systems during sleeping in winter, such as Chinese Kang, air conditioning system. However, these two system have some unsatisfactory aspects, such as air pollution for fuel burning from Chinese Kang and drought issue for air conditioning system. Air Source Heat Pump (ASHP) system as a highly reliable system with long lifespan might be an available heat source for traditional Chinese Kang, which would solve the problem of waste pollution from Chinese Kang as well as keep the original advantages of Chinese Kang, like localized heating and uniform airflow distribution. Based on this assumption, a novel system called bed-based system powered by ASHP was proposed. To prove the feasibility of the novel system and find out the difference of thermal performance to conventional heating system, the first step is creating the models of the novel bed-based system and a conventional convection-based system respectively for simulation by using Computational Fluid Dynamics (CFD). After validating the models using experiment data, 5 groups of the total 10 cases were studied using Fluent. (Case study A: Case 1 to 4, Case study B: Case 4 & 5, Case study C: Case 5 & 8, Case study D: Case 6 & 9, Case study E: Case 7 & 10). Case 1 to Case 5 present the difference of thermal performance for bed-based system powered by ASHP under different thickness of traditional cotton covering bedding materials in bedroom with one heat transfer wall (followed the experimental conditions). Case 6 and Case 7 demonstrate the simulated results for the heating performance of the novel system under six heat transfer walls (to simulate a real bedroom). Cases 8 to 10 are comparative simulations using conventional convection-based system heated by ASHP corresponding to Cases 5 to 7. According to the results from Cases 1 to 5, the novel system with 5 mm mattress and 15 mm quilt may provide ideal heating performance for sleeping people under experimental conditions. Since the thickness of mattress decreasing from Case study A and the thickness of quilt decreasing in Case study B, the average temperature in occupied zone (the location of human sleep) increases from 5.77 °C in Case 1 to 15.67 °C in Case 5 with only 0.8% difference to the ideal state (16.8 °C). However, system with the same covering materials could not perform an ideal heating performance with low average temperature (10.20 °C) in Case 6, while the heating performance of the novel system without covering bedding materials is basically satisfactory based on the results in Case 7, which is 16.29 °C for average temperature in occupied zone. Compared to convection-based system, bed-based system with high ADPI (80% in Case study E) has better thermal performance for sleeping environment due to moderate airflow (less than 0.1m/s) as well as uniform air distribution based on the analysis of Case study C to E. Therefore, finding suitable covering bedding materials to improve the comfort for users and optimize the novel system would be the further work. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 991022370853903411.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 3.62 MB | Adobe PDF | View/Open |
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