Solar heating and air conditioning

In order to understand the solar heat pump heating system, a phase-change storage solar heat pump heating system based on cloud computing is proposed. This paper first introduces the solar heat pump as a phase change energy storage that can change four types of heat depending on the weather conditions and significantly reduce the energy consumption of the system. Second, through the special design of the energy storage capacitor, in addition adjusting the energy distribution of the solar heat pump system, it can also improve the reliability of supply and demand between the solar heat pump system and the building heating system, improve the level of solar energy consumption, but also improve the low temperature of the pump milk temperature, and improve the solar heat up quickly to achieve the goal of improving the overall performance of the heat pump. Finally, this paper takes an urban ?electric coal? house as a research object to investigate the hot air efficiency of solar heat pumps. This paper analyzes the daytime solar heat pump mode, the nighttime energy storage mode under extreme conditions, and the air source heat pump mode. And shows the research results that the solar heat pump has good heating efficiency and the highest solar COP. Will be heat pump is 5.28 solar energy average heat pump COP is 2.13. In very bad weather, solar heat pumps work better.

In this work a new highly compact solar thermal heat pump system for space heating and domestic hot water preparation will be presented in detail. It was developed within the European project “MacSheep”. The aim of the project is to build four different solar heat pump systems, which achieve 25 % electric energy savings compared to the state of the art solar heat pump heating systems, while still being cost-competitive. Within the MacSheep project, four different developing groups developed different system concepts to reach this project goal. The system, which is presented in this paper, was developed and designed by the following partners; Energie Solaire SA (industrial partner), Institute of Thermal Engineering (research partner) and the Institute for Solar Technology SPF (research partner). A key component of the system is a novel brine-to-water heat pump prototype with a speed controlled compressor, an economizer refrigerant cycle and a desuperheater. The heat pump was optimized for low source temperatures, in order to be compatible with concepts that use only unglazed selective collectors as heat source. A key element was the integration of heat pump, storage, and hydraulic connections into one compact system design. Further developments are: a combi-storage, which is optimized for heat pump use, and selective unglazed c ollectors with a new selective coating. The compact designed heat storage, heat pump and hydraulic solution is placed under one high performing insulating shell built of vacuum insulation panels. The annual simulation results, which were validated with component tests in the lab, show very promising results for the whole system. The electric savings compared with the state of the art system are expected around 28 % and the improvement of the seasonal performance factor (SPF) of the whole system is around + 40 %. These values will be compared with a whole system hardware in the loop benchmark test in autumn 2015.

Two demonstrations of solar air-conditioning and heating system in office building are introduced, one is solar heating system with seasonal storage, flat plate solar collector integrated into external wall, the solar fraction for space heating is 25%, another is solar-assisted air-conditioning system, evacuated tube solar collector integrated with flat roof, the solar fraction for space heating is 20%, for air-conditioning is 50%. The auxiliary energy equipment is ground-source heat pump system. The control strategy for solar system and auxiliary energy system are also introduced. The project is financial by National Renewable Energy Fund of China.

In the north of Graz, Austria, a large scale solar thermal system (gross collector area: 3885 m²) was installed in 2009 primarily to supply solar heat to a district heating (DH) network especially in summer and to cover part of the heat demand of the on-site buildings. In order to reduce the auxiliary heat needed for the on-site buildings and to prolong the operation time of the solar thermal system, a heat pump, which uses the solar collector loop as exclusive heat source, was installed later on. This way solar heat that is available at temperatures too low for direct solar charging of the TES (thermal energy storage) can still be used. After having performed dynamic system simulations of the installation without the heat pump in TRNSYS to validate the simulation model, the heat pump was implemented into the simulation model. Applying different control strategies to the solar heat pump system an increase of the solar fraction for the heating period (October to March) from 20.5 % without the heat pump up to 33.0 % with heat pump could be reached in the simulations. The interaction between solar thermal system and heat pump in this special configuration turned out to be challenging in terms of control optimization; hydraulic decoupling of the two units is recommended. Based on onsite measurements the performance of the system in February 2013 is evaluated

In order to assess in detail the state of the technology for solar heating and cooling of buildings, five 2-day meetings were held. The meeting subjects were solar collectors, thermal storage, air conditioning and heat pumps, systems and controls, and non-engineering aspects of solar energy. This is a condensation of these meetings, presenting for each topic discussed the details of the state of the art, the problem areas, and the objectives of necessary research and development. The existing state of technology for solar heating and cooling presents a mixed picture. Liquid-heating flat-plate solar collectors, for example, are in a rather mature stage, and there is a small, viable industry producing components. Even here, however, there are problems of materials which, if solved, can reduce collector cost, improve performance, or increase lifetime. In other areas such as, for example, desiccant chillers, passive concepts, and many of the systems categories, the technology is at an early stage of evolution, and much research and development remain to be done.

Economic evaluation and annual performance analysis of a novel series-coupled PV/T and solar TC with solar direct expansion heat pump system: An experimental and numerical study

Performance of combined solar-heat pump systems

Solar Heating and Cooling in Buildings – How Sustainable?

Society’s use of fossil fuels has led to increasingly high levels of CO2 in the atmosphere. These levels have been linked to global average temperature rises, and increases in the severity and frequency of major weather events. To combat these effects, nations around the world have committed to reducing their CO2 emissions, and transition to renewable energy. This thesis focuses on the development of a novel solar heating system, which combines a hybrid solar panel and cascade heat pump. The thesis begins by presenting a high-level literature review of solar and heat pump technologies, followed by the initial design development of the system. Two design iterations are presented, illustrating that the final design was selected because it exhibits improved peak heat output, and reduced sensitivity to panel temperature. Next, a manuscript-based chapter is presented that focuses on utilizing the proposed solar heating system for water distillation. Case studies are presented that compare the performance of the proposed system with a solar still at four different locations. The final conclusion from these studies is that using the proposed system offers area-based performance improvements of 780% compared to a basic solar still. A second manuscript-based study is then presented, which focuses on utilizing the proposed solar heating system for domestic hot water production. Additional case studies are detailed that compare the proposed system to an evacuated tube design, and a single heat pump. The conclusions from these studies are that the proposed system exceeds the performance of the evacuated tube system by up to 64%, and that the proposed system is most beneficial during seasons with higher average dry-bulb temperatures, and increased solar irradiation. A final manuscript-based study is then presented, which focuses on a methodology for improving alternate mode thermal performance estimates for hybrid solar panels. The conclusion from this study is that the proposed methodology can successfully estimate thermal performance within 5% of actual values. Each of these studies contributes to the project goal of developing a novel solar energy heating system, which can be further developed to reduce global CO2 emissions, and reduce the effects of climate change.

Energy resource requirements of a solar heating system

Liquid desiccant has been widely used in various solar energy applications, such as air conditioning and food drying. Especially, in the emerging solar desiccant air conditioning system, the regenerator, where the diluted solution is concentrated, plays an important role. Using the open-cycle solar collectors/regenerators (C/R) to concentrate the dilute solution is an effective way to utilize low-grade solar thermal energy to regenerate desiccant solution for air conditioning. The desiccant solution itself is a heat-collecting fluid and the regeneration process could be enhanced in this arrangement. To evaluate its thermal performance, a lab-scale experiment has been conducted using lithium bromide (LiBr) solution. The effects of ambient weather variables (solar radiation, air temperature, relative humidity) and operation conditions (air mass flow rate, solution flow rate, air inlet temperature, solution inlet temperature, and solution concentration) on the solar regeneration parallel flow configurations have been experimentally investigated. To further investigate the heat- and mass-transfer phenomenon inside the solar C/R, the heat- and mass-transfer coefficients are calculated based on the experimental data using multi-dimensional optimization method. Unlike those traditional correlations available in the literature, the effects of inlet conditions of the air and solution on the heat- and mass-transfer coefficients are clearly identified. Applying these correlations to the simulation model of the solar C/R and comparing the predicted values with the experimental values, the accuracy is satisfactory and can be applied to the further investigation for the thermodynamic performance of the solar desiccant air conditioning system.

Experimental research on a solar air-source heat pump system with phase change energy storage

Solar Collectors cooled directly with Refrigerant 12 and acting as the evaporator of a solar source heat pump system has been experimentally investigated. The refrigerant cooled solar collector may be operated at an evaporation temperature lower than its ambient temperature and thus has an efficiency higher than that of the flat plate solar collectors in conventional systems.

This thesis presents the investigation into the feasibility of solar assisted vapour compression air conditioning system in providing thermal comfort in Malaysia. Conventional vapour compression air conditioning system consumes large amount of energy which is a clear disadvantage considering the high fuel price and electric tariff. Therefore, this research was intended to develop and integrate solar hybrid system into conventional air conditioning system which provides the same cooling load with considerably less electricity demand. In addition, Microsoft Excel spreadsheet is also prepared to facilitate the calculation of refrigerant temperature and energy saving of the system. DC compressor and evacuated tube solar compressor is introduced to assist the electric compressor in compressing the refrigerant, effectively reducing the air conditioning electricity consumption by up to 45%. Meanwhile, during night time, energy saving is only contributed by the DC compressor which reduces electricity consumption by up to 25%. The development and utilization of solar energy reduces the dependency on energy generation from fossil fuel which emits greenhouse gases and worsen the global warming while also pushing Malaysia one step closer to their aim in reducing CO₂ emissions and harnessing renewable energy. Malaysia as a tropical country with average solar radiation of 4500Wh/m² per day, has endless potential in solar energy (Borhanazad, 2013). This project provides technical overview which involves the study of solar energy conversion system and viability of solar hybrid vapour compression air conditioning system under Malaysia climate.

A parallel solar augmented heat pump system has been experimentally evaluated in TECH House IV for three heating seasons between fall 1979 and spring 1982. Several changes were made in the operation of the system during the three year period. During 1979–1980, the use of on-peak purchased energy was minimized by charging the pebble bin in the off-peak period with a resistance duct heater. This configuration resulted in 83 percent of the purchased energy occurring in the off-peak period but the seasonal performance factor was only 1.61. During 1980–1981, the system was operated in the normal mode without the use of the off-peak heater. The seasonal performance factor then increased to 2.56. During 1981–1982, the mode of operation was the same as 1980–1981, but new outer cover sheets were installed and the inner cover sheet was eliminated resulting in a single glazed collector. The seasonal performance factor for the 1981–1982 season was measured to be 2.11.