Wu, Zhangxiang;
Jiang, Yan;
Wang, Yaran;
You, Shijun;
Zhang, Huan;
Liu, Sujie;
Fan, Xianwang;
... Wei, Shen; + view all
(2023)
Investigating the performance of heat exchangers in absorption heat pump systems using both numerical and experimental methods.
Energy Conversion and Management
, 278
, Article 116744. 10.1016/j.enconman.2023.116744.
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Abstract
To achieve better heating efficiency and lower CO2 emission, this study has proposed an air source absorption heat pump system with a tube-finned evaporator, a vertical falling film absorber, and a generator. To analyze both heat and mass transfer performances and optimize the sizes of both the absorber and the generator, a distributed parameter model and a two-dimensional numerical model have been adopted, both validated. To develop an environmentally efficient working fluid pair for absorption heating for cold climate, a calculation method adopting fugacity and activity models was developed. The defrosting control strategy of this system was developed based on a spatial and temporal frost development model, which determines the characteristics of frost distribution, frost growth, and frost inhomogeneity. To evaluate the functionality of this system, a test rig was constructed, with a heating capacity of 36.88 kW, a coefficient of performance of 1.54 under evaporation temperature and supply water temperature of −9.2 °C and 38.4 °C, respectively. Validation results showed a 1.5 % higher prediction accuracy for the two-dimensional model with correction, comparing to the distributed parameter model. R134a-DMF and R161-DMF were recommended at an ambient temperature of −2 °C. This is because with ambient temperature of −7 °C and supply water temperature of 41 °C, the predicted coefficient of performance was 1.04 and 1.06 for R134a-DMF and R161-DMF, respectively. The frost prediction indicated that at the time of 3,600 s, the thickness of the frost layer in the heavy frost area was 0.94 mm, with a total frost mass of 3,995 g. Compared with the initial stage, the sensible and latent heat transfer rates decreased by 22.1 % and 24.2 %, respectively.
| Type: | Article |
|---|---|
| Title: | Investigating the performance of heat exchangers in absorption heat pump systems using both numerical and experimental methods |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.enconman.2023.116744 |
| Publisher version: | https://doi.org/10.1016/j.enconman.2023.116744 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher's terms and conditions. |
| Keywords: | Absorption heat pump, Heat exchanger, Numerical model, Working fluid pair, Frost distribution characteristic |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10164748 |
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