Studies of Heat Pumps Using Direct Expansion Solar Collectors

Ito, Sadasuke; Miura, Naokatsu; Takano, Yasushi

doi:10.1299/jsmeenv.2002.12.493

Cited by 4 publications

(5 citation statements)

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“…In Japan, several studies were carried out, such as a PVT demonstration project [88], a PVT module study [89] and studies for PVT as source for a heat pump [90][91][92]253]. Huang et al [93,94] did a study on unglazed PVT at the National University of Taiwan.…”

Section: History Of Pvt Water Heatingmentioning

confidence: 99%

“…It was found that high COP's could be found, whereas the PV was efficiently cooled. Ito et al [90] present analytical results on the sensitivity of the system to collector area, W/D and thickness of the collector plate. In a further research, Ito et al [253] indicate that under low irradiance conditions, the COP of the heat pump is very low, due to the fact that a flatplate collector with an insulated rear is not optimised for extracting heat from the ambient air.…”

Section: Article In Pressmentioning

confidence: 99%

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Flat-plate PV-Thermal collectors and systems: A review

Zondag

2008

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Section: History Of Pvt Water Heatingmentioning

confidence: 99%

Section: Article In Pressmentioning

confidence: 99%

Flat-plate PV-Thermal collectors and systems: A review

Zondag

2008

Renewable and Sustainable Energy Reviews

562

220

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“…At a later time, Aziz and Chaturvedi [6] experimented with the same DXSAHP design and concluded that a variation in the mass flow of the refrigerant affects significantly its heat transfer coefficient, and that the change in piping diameter and collector pressure are irrelevant, being the collector size the most critical dimension that affects the performance of the working fluid. Other authors such as Ito et al [7] also experimented with the collector dimensions and construction, concluding that they do not have a significant effect on the DXSAHP's performance, as long as it is not working under extreme conditions and the solar radiation index is at its maximum. On the other hand, to comprehend the heat transfer capabilities of the DXSAHP during non-radiation conditions Tabatabaei et al [8] developed an analytical model to analyze an air-to-water heat pump for space heating, considering only convection phenomena and the temperature difference between the heat source and sink.…”

Section: Analysis Of the Solar Collectorsmentioning

confidence: 99%

Mathematical Thermal Modelling of a Direct-Expansion Solar-Assisted Heat Pump Using Multi-Objective Optimization Based on the Energy Demand

León-Ruiz

Carvajal-Mariscal

2018

Energies

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An analytical model is proposed to evaluate the performance of a Direct Expansion Solar-Assisted Heat Pump under a given environmental condition. These thermal machines commonly employ uncovered flat plate solar collectors, and given this, the convection phenomenon is taken into account as well as the effect of the diffuse and reflected solar radiation in addition to the normal beam radiation absorbed by the tilted surface of the collectors. The heat pump cycle is modelled through a first law of thermodynamics approach in order to compute the heat yielded through condensation and the minimum heat required by the volume of water in the thermal storage unit. Consequently, the thermal capacity of the heat pump, the ratio at which the system yields heat to a given load of water, is calculated and discussed. The results of the model proposed are compared with the experimental data provided by three research papers with experiments conducted in different geographic coordinates and test rigs operating during diverse atmospheric conditions. A maximum relative error of 20% was obtained and furthermore, a statistical analysis of the data was conducted having found that there is no significant statistical difference between the analytical and experimental data samples within the 95% confidence interval. Finally, based on the thermal capacity, the performance of the heat pump is evaluated and a multi-objective optimization technique is implemented to obtain the best possible combination of factors to further enhance the performance of the heat pump.

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“…The other collector, the convective evaporator, was made of a copper tube with thin aluminium fins. It was shown that using the two collectors in parallel raised COP hp at low solar insolation [17].…”

Section: Related Heating Systemsmentioning

confidence: 99%

A Domestic Solar/Heat Pump Heating System Incorporating Latent and Stratified Thermal Storage

Trinkl

̈rner

Hanby

2008

ASME 2008 2nd International Conference on Energy Sustainability, Volume 2

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Both solar and heat pump heating systems are innovative technologies for sustaining ecological heat generation. They are gaining more and more importance due to the accelerating pace of climate change and the rising cost of limited fossil resources. Against this background, a heating system combining solar thermal collectors, heat pump, stratified thermal storage and water/ice latent heat storage has been investigated.In order to investigate and optimise the heating system, a dynamic system simulation model was developed. On this basis, a fundamental control strategy was derived for the overall co-ordination of the heating system with particular regard to the performance of the two storage tanks. In a simulation study, a fundamental investigation of the heating system configuration was carried out and optimisation derived for the system control as well as the selection of components and their dimensioning. The influence of different parameters on the system performance was identified, where the collector area and the latent heat storage volume were found to be the predominant parameters for system dimensioning.For a modern one-family house, a solar collector area of 30m² and a latent heat store volume of 12.5m³ are proposed. In this configuration, the heating system reaches a seasonal performance factor of 4.6, meaning that 78% of the building's and users' heat demand are delivered by solar energy. The results show that the solar / heat pump heating system can give an acceptable performance using up-to-date components in a state-ofthe-art building.A novel but most significant component of the heating system is the latent heat store, working with water / ice as phase change material. For that reason, the store was developed in a systematic manner with special regard to the heat exchangers. Based on a detailed specification and a functional analysis, concept solutions were investigated and evaluated. A sheet matrix heat exchanger was eventually chosen as it fulfils the specialised requirements of the heating system. The heat exchanger's behaviour and its performance during phase change were analysed in laboratory tests. In addition, a storage tank design was developed and a preliminary storage dimensioning carried out for the heating system as defined by the simulations, showing that five polymer tanks with 3.3m³ each and 14 sheet matrix heat exchangers in each tank are required.

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Studies of Heat Pumps Using Direct Expansion Solar Collectors

Cited by 4 publications

References 0 publications

Flat-plate PV-Thermal collectors and systems: A review

Flat-plate PV-Thermal collectors and systems: A review

Mathematical Thermal Modelling of a Direct-Expansion Solar-Assisted Heat Pump Using Multi-Objective Optimization Based on the Energy Demand

A Domestic Solar/Heat Pump Heating System Incorporating Latent and Stratified Thermal Storage

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