Civil Engineering Reference
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and the corresponding electricity conversion efficiency was 8.56 %, during the late
summer in Hong Kong. With the PV/T wall, the space thermal loads can be
significantly reduced both in summer and in winter, leading to substantial energy
savings.
Zhao et al. (
2009
) designed two experimental prototypes by integrating the flat-
plate heat pipe with the mono-ci PV cells at the effective area of 0.0625 m
2
, while
the surplus heat was taken away, respectively, via the natural air flow and passive
water circulation. In comparison with the solely PV system, the PV/T modules
were found to be able to achieve the enhanced electrical efficiencies of 2.6 and
3 %, and the reduced cell temperatures of 4.7 and 8 C, respectively, for air- and
water-based conditions.
Ji et al. (
2009
) developed a novel solar PV/T heat pump (PV/T-SAHP) system
that combined a Rankine refrigeration cycle with a PV/T solar collector.
A dynamic model for the PV evaporator was established using the distributed
parameter approach to investigate the effect of the refrigerant parameters (e.g.
pressure, temperature, vapour quality and enthalpy) onto the system's solar effi-
ciencies and study the temperature distribution across the evaporator channels. The
results indicated that the PV electrical efficiency and evaporator thermal efficiency
are around 12 and 50 %, respectively, during the testing period in Hefei, China.
On the basis of the above work, Ji et al. (
2008
) carried out the testing of the
system under a range of operational conditions. The results indicated that the PV-
SAHP system has a higher coefficient of performance (COP) than the conventional
heat pump system and the PV's electrical efficiency is also higher. The COP of the
heat pump was able to achieve 10.4, while the average COP value of the traditional
heat pumps was around 5.4. The average PV solar efficiency was around 13.4 %.
The highest overall coefficient of performance (COP—peak), taking into account
the performance of PVs and evaporators, was around 16.1.
Zhao et al. (
2011
) designed a novel PV/e roof module to act as the roof element,
electricity generator and the evaporator of a heat pump system. The energy profiles
and system operating conditions were analysed, and temperature distribution
across the module layers was simulated. This study indicated that the combined
system should operate at 10 C of evaporation and 60 C of condensation tem-
perature. Borosilicate as a top cover has better thermal performance than poly-
carbonate and glass, while the mono-crystalline photovoltaic cells are of higher
electrical efficiency over the polycrystalline and thin films. Under a typical Not-
tingham (UK) operating condition, the modules would achieve 55 % of thermal
efficiency and 19 % of electrical efficiency, while the module-based heat pump
system would have an overall efficiency of above 70 %. It was also addressed that
the integration of the PV cells and evaporation coil into a prefabricated roof would
lead to large saving in both capital and running costs over separate arrangements
of PV, heat pump and roof structure.
Apart from the above reports, many other achievements in this subject have
been found and a few more examples of these are briefed as below.
For air-based PV/T, Komp and Reeser (
1987
) reported on the design and
installation of a stationary concentrating glazed roof-integrated PV air collector for
