| 1. |
- He, Wei, et al.
(författare)
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Operational performance of a novel heat pump assisted solar facade loop-heat-pipe water heating system
- 2015
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 146, s. 371-382
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Tidskriftsartikel (refereegranskat)abstract
- This paper aims to present an investigation into the operational performance of a novel heat pump assisted solar façade loop-heat-pipe (LHP) water heating system using both theoretical and experimental methods. This involved (1) development of a computer numerical model; (2) simulation of the operational performance of the system by using the model; (3) test rig construction; and (4) dedicated experiment for verification of the model. It was found that the established model is able to predict the operational performance of the system at a reasonable accuracy. Analyses of the research results indicated that under the selected testing conditions, the average thermal efficiency of the LHP module was around 71%, much higher than that of the loop heat pipe without heat pump assistance. The thermal efficiency of the LHP module grew when the heat pump was turned-on and fell when the heat pump was turned-off. The water temperature remained a steadily growing trend throughout the heat pump turned-on period. Neglecting the heat loss of the water tank, the highest coefficient of the performance could reach up to 6.14 and its average value was around 4.93. In overall, the system is a new façade integrated, highly efficient and aesthetically appealing solar water heating configuration; wide deployment of the system will help reduce fossil fuel consumption in the building sector and carbon emission to the environment.
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| 2. |
- He, Wei, et al.
(författare)
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Theoretical investigation of the thermal performance of a novel solar loop-heat-pipe facade-based heat pump water heating system
- 2014
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788 .- 1872-6178. ; 77, s. 180-191
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the paper was to present a dedicated theoretical investigation into the thermal performance of a novel solar loop-heat-pipe façade based heat pump water heating system. This involved thermo-fluid analyses, computer numerical model development, the model running up, modelling result analyses and conclusion. An energy balance network was established on each part and the whole range of the system to address the associated energy conversion and transfer processes. On basis of this, a computer numerical model was developed and run up to predict the thermal performance of such a system at different system configurations, layouts and operational conditions. It was suggested that the loop heat pipes could be filled with either water, R134a, R22 or R600a; of which R600a is the favourite working fluid owing to its relatively larger heat transfer capacity and positive pressure in operation. Variations in the system configuration, i.e., glazing covers, heat exchangers, would lead to identifiable differences in the thermal performance of the system, represented by the thermal efficiency and COP. Furthermore, impact of the external operational parameters, i.e., solar radiation and ambient air temperature, to the system's thermal performance was also investigated. The research was based on an innovative loop-heat-pipe façade and came up with useful results reflecting the thermal performance of the combined system between the façade and heat pump. This would help promote development and market penetration of such an innovative solar heating technology, and thus contribute to achieving the global targets in energy saving and carbon emission reduction.
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