Imperial College London
Alternate

Dr James Freeman

Faculty of Engineering, Department of Chemical Engineering

Academic Visitor
 
 
 
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Contact

 

+44 (0)20 7594 1442j.freeman12

 
 
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Location

 

425Bone BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@inproceedings{Harraz:2019,
author = {Harraz, AA and Najjaran, A and Sacks, R and Freeman, J and Olympios, AV and Mac, Dowell N and Markides, CN},
pages = {1045--1056},
title = {Experimentally validated simulations of a diffusion absorption refrigeration system},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - CPAPER
AB  - Diffusion absorption refrigeration (DAR) is a small-scale, thermally-driven cooling technology that operates passively without the need for mechanical or electrical inputs. Due to the lack of a compressor, DAR systems are charged with an auxiliary gas to enable single-pressure operation. Although DAR units have a simple construction and are easy to operate, their modelling presents challenges arising from the complexity of the physical processes that take place and govern operation. Few experimentally validated models offer a reliable prediction of the DAR system performance over a wide range of operating conditions. This paper combines results from experimental investigations on a laboratory-scale ammonia-water-hydrogen DAR system with a nominal cooling output of ∼100 W with model predictions of the performance characteristics of this system. In previous work, the DAR cycle was modelled using first-law thermodynamic analysis in the gPROMS environment for a single cooling delivery temperature and a single-charge pressure, using a group-contribution equation-of-state based on the statistical associating fluid theory (SAFT). Here, extended model validation is performed to investigate the effect of key operating parameters on system performance, including the generator heat input (varied from 150 W to 700 W), the cooling delivery temperature (set to two levels: 5 C and 23 C) and the system charge pressure (18 bar and 21 bar). The measured coefficient of performance (COP) was between 0.02 and 0.29. The present model predicts the maximum COP well over the heat-input range from 250 W to 550 W. Hence, the model shows good agreement with experiments, particularly when the heat-input rate is at or below the system’s design-point. Conclusions are drawn concerning the ability of models to predict this complex technology, with emphasis on part-load and off-design operation which is crucial, e.g., in solar applications.
AU  - Harraz,AA
AU  - Najjaran,A
AU  - Sacks,R
AU  - Freeman,J
AU  - Olympios,AV
AU  - Mac,Dowell N
AU  - Markides,CN
EP  - 1056
PY  - 2019///
SP  - 1045
TI  - Experimentally validated simulations of a diffusion absorption refrigeration system
ER  -
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