Efficiency analysis of flat plate collectors for building facade integration

Growing population, depleting fossil fuels, economic expansions, and energy intensive life style demand are resulting in higher energy prices. We use energy as of heat and electricity, which can directly be obtained from sun using thermal collectors and solar cells. Solar thermal systems are gaining attention for water and space heating applications due to green aspects of solar energy. A solar thermal collector is a vital part of solar thermal energy system to absorb radiant energy from the sun. In this study, a solar water heating (SWH) system has been designed and simulated in the TRNSYS ® software using thermal and chemical properties of heat transfer fluids using REFPROP for dwellings located on ±31° latitudes (+31 Lahore in Pakistan and -31° Perth in Australia). We present an efficiency parametric optimization-based model for water and space heating. Simulation results for four types of solar thermal collectors are presented, and performance is analyzed on the basis of output temperature ( T out ), solar fraction ( f ), and collector efficiency ( η ). This study evaluates the comparative performance of evacuated tube collector (ETC), flat-plate collector (FPC), compound parabolic concentrator (CPC), and thermosiphon-driven systems. Our findings conclude the evacuated glass tube collector achieves the highest solar fraction, i.e., 50% of demand coverage during August in Pakistan and February in Australia, with an overall average of 43% annually.

Renewable energy systems such as wind, solar and biomass are significantly more land intensive than traditional fossil fuels. Renewable energy increases diversity of energy supplies and can replace diminishing fossil fuel resources over the long run; their use in place of fossil fuels can substantially reduce greenhouse gases and other pollutants. Application of solar energy for domestic and industrial heating purposes has become more popular. In this paper, reduced land use of flat plate collectors for same output with solar point collector is analysed. However the effectiveness of presently used flat plate collectors is low due to the moving nature of the energy source. So the performance of solar flat plate collector is effectively improved by using a novel system called solar point collector. Also an attempt has been made to compare the performance of flat plate collector with that of solar point thermal energy collector by conducting experiments. Experiments were conducted for a week during which the atmospheric conditions were almost uniform and data was collected both flat plate collector and solar point collector for various flow conditions.

PurposeTo cover the main contributions and developments in solar thermal collectors through focusing on materials, heat transfer characteristics and manufacturing challenges.Design/methodology/approachA range of published papers and internet research including research work on various solar thermal collectors (flat plate, evacuated tubes, and heat pipe tube) were used. Evaluation of solar collectors performance is critiqued to aid solar technologies make the transition into a specific dominant solar collector. The sources are sorted into sections: finding an academic job, general advice, teaching, research and publishing, tenure and organizations.FindingsProvides information about types of solar thermal collectors, indicating what can be added by using evacuated tube collectors instead of flat plate collectors and what can be added by using heat pipe collectors instead of evacuated tubes.Research limitations/implicationsFocusing only on three types of solar thermal collectors (flat plate, evacuated tubes, and heat pipe tube).Practical implicationsUseful source of information for consultancy and impartial advice for graduate students planning to do research in solar thermal technologies.Originality/valueThis paper fulfils identified information about materials and heat transfer properties of materials and manufacturing challenges of these three solar thermal collectors.

Techno-economic analysis of a hybrid district heating with borehole thermal storage for various solar collectors and climate zones in Pakistan

An experimental study is carried out to investigate the heat transfer characteristics of silver/water nanofluid in a solar flatplate collector. The solar radiation heat flux varies between 800 W/m2and 1000W/m2, and the particle concentration varies between 0.01%, 0.03%, and 0.04%. The fluid Reynolds number varies from 5000 to 25000. The influence of radiation heat flux, mass flow rate of nanofluid, inlet temperature into the solar collector, and volume concentration of the particle on the convective heat transfer coefficient and the collector efficiency are studied. Both parameters increase with increase in the particle volume concentration and flow rate. The maximum percentage increase obtained in the convective heat transfer coefficient is 18.4% for the 0.04% volume concentration at a Reynolds number of 25000. An increase in the performance of nanofluid is also witnessed when compared to the base fluid, which has a strong dependency on volume concentration and mass flow rate. MgO. The nanofluid achieved a 3°C temperature difference during the daytime peak solar radiation compared with the base fluids. With a concentration of 0.2% ZnO, a temperature difference of 2.55°C for daytime and 1°C for nighttime was reached, and this was determined to be the most attractive option for solar energy utilization. Yousefi et al. [15] witnessed a 28% performance improvement in a flat-plate collector when it was operated with water-Al2O nanofluids. Tyagi [16] theoretically compared the conventional flat-plate collector with a direct absorption solar collector (DAC) and observed the former to be 10% more efficient. Otanicar [17] studied the conomic and environmental influences of using nanofluids to enhance solar collector efficiency with conventional solar collectors. Dongxiao et al. [18] presented excellent photothermal properties of carbon-black aqueous nanofluids at highvolume fractions. Further work on nanofluids’ application to direct solar absorption has been carried out by Lijuan Mu [19] using a custom-made direct solar absorber. The radiative properties of several nanofluids are tested for the highest temperature difference across the heat exchangers. Based on the above-mentioned review of the literature, it has been clearly observed that most of the previous studies on solar flat-plate collectors were conducted using metal oxide nanoparticles in relatively high concentrations. These high concentrations of metal oxide nanoparticles cause a higher pressure drop that then requires a higher pumping power. Since a limited number of studies exists in the literature with respect to pure metal nanoparticles, it is recommended to study the heat transfer characteristics of pure metal nanoparticles with relatively low concentrations (

Recent advances on nanofluids for low to medium temperature solar collectors: energy, exergy, economic analysis and environmental impact

Cosmic power is one of the numerous renewable energy sources that can use in a Photovoltaic (PV) system or Thermal. Solar collectors play a crucial role in solar thermal systems. They convert solar radiation into heat and transfer the heat to working fluids Such as water or air. The Flat-plate collectors are the numerous common type of solar collectors and typically used as a water heater or air heater. These collectors have low efficiency and low outlet temperature. Recently, many scientists have attempted to improve the efficiency and performance of flat-plate collectors via different methods. This review paper describes the results of the experimentation carried out to study and compare the performance of the modified flat plate collector having increasing riser tube diameter and reducing riser tube length with the conventional ISI marked solar liquid flat plate collector. To study, the comparative performance characteristics of a modified flat plate collector with ISI flat plate collector operated under natural circulation mode. The suggested design found to be better than the existing ISI design of the absorber plate from an efficiency point of view. The actual useful heat gain (Qu) in the suggested design understudy found to be more by 30% than that in the case of ISI collector. However, the modified flat plate collector found to operate at a relatively lower exit temperature than the conventional ISI marked collector.

Prediction of long-term performance of solar collectors is required for optimum solar system design. Availability of solar radiation above critical level ascertains utilization of solar radiation for useful energy gain by the systems. F chart method or the utilizability methods developed by Klein, Collares-Pereira, and Rabl are mainly used to simulate long-term performance of solar flat plate collectors. In this paper, long-term performance analysis of two different types of solar thermal collectors has been studied using utilizability method. Long-term radiation data on tilted surface has been simulated using Klucher’s model and has been used to estimate daily utilizability and useful energy gain by a flat plate collector and evacuated tube collector. The annual performance of these two types of collectors is compared under different climatic conditions namely cold desert climate and hot semi-arid climate, to understand applicability of these systems to meet the energy demand of these places. It has been observed that evacuated tube collectors show better performance during winter months compared to flat plate collectors. The F chart method is also used to find the fraction of demand of hot water for domestic applications that can be met by a flat plate collector system for different collector area. It has been observed that 30–55% of the demand can be met by flat plate collector water heating system based on the collector area.KeywordsLong-term performance analysisUtilizabilityKlucher modelFlat plate collectorEvacuated tube collector

Heat driven sorption based cooling systems are gaining interest as they are environmentally friendly and have the potential to save precious fossil fuel resources. Low grade thermal sources like solar or waste heat can run a silica gel-water paired adsorption chiller to generate chilled water below 10°C. However, the performance of the adsorption chillers is poor when compared to vapour absorption or vapour compression based cooling systems. An effort has been made in this work to analyze the influence of different operating parameters on the cooling performance of a silica gel-water adsorption chiller driven by hot water from an evacuated tube solar thermal collector system. A cycle simulation program verifies the effect of heat transfer fluids’ temperatures and the cycle time on the cooling capacity and COP of the chiller. An optimized operating strategy of the chiller, based on either maximum cooling capacity or maximum COP, may be found out using this work. Cycle time, driving source temperature and the cooling water temperature are found to considerably affect the performance of the chiller. Keywords: Adsorption chiller, solar heat, silica gel-water, cycle simulation, parametric study Cite this Article Chakraborty A, Choudhury B. Parametric Study of a Solar Heat Driven Silica Gel–Water Paired Adsorption Chiller. Journal of Alternate Energy Sources & Technologies. 2015; 6(2): 19–29p.

<p dir="ltr">This dissertation focuses on integrating novel hybrid solar photovoltaic/thermal (PV/T) collectors and thermal storage into building energy systems for cold climates. The research comprises three papers that investigate various aspects of these systems.</p><p dir="ltr"> The first study compares the performance of four different solar-based systems for domestic hot water (DHW) production in Canada's residential sector. A microchannel (MC) solar thermal collector and a microchannel-based hybrid PV/T collector, utilizing microchannel heat exchangers, were fabricated and then modelled and simulated using TRNSYS software. Integration with a water-to-water heat pump (HP) improves the systems' efficiency and solar fraction. The results show that the microchannel solar thermal and PVT-HP system achieves the highest annual solar fraction, outperforming conventional solar thermal and PV-resistance systems. It performs superior in cold climates, with a 10% to 35% higher solar fraction during winter. Moreover, the MC-based systems demonstrate less sensitivity to collector tilt angles, which is more suitable for facade integration in high-rise buildings. </p><p dir="ltr">There are some limitations and potential enhancement opportunities for the first study that influenced the system's efficiency. Another study is conducted to enhance the thermal storage system to improve the system's efficiency. The second study proposes an innovative approach to building-integrated thermal storage using insulated concrete form (ICF) foundation walls in cold climates. The surplus solar thermal energy is stored within the high thermal capacity of the ICF walls. Coupled with a water-to-water heat pump, the ICF walls and solar thermal collectors fulfill the combined space and DHW heating demand by up to 72%. Simulation results reveal that the ICF-based system achieves a higher solar fraction than systems with large water tanks. Incorporating PVT collectors increases the overall solar fraction further to 82%. The proposed ICF-based systems perform optimally at high tilt angles and are also suitable for vertically mounted solar systems in high-rise buildings with limited roof areas. </p><p dir="ltr">As the solar collector has a significant role in the system’s total efficiency, a new type of PVT collector is being studied to enhance the system’s efficiency. The third study focuses on the design of a cost-effective and efficient air-based PV/T collector. The proposed PVT utilizes an industrialized heat exchanger, GRIPMetal or GM, as the absorber plate. The GM plates, consisting of spikes and cavities, improve the convective heat transfer coefficient in the air channel, resulting in significant enhancements in electrical and thermal efficiencies. Through numerical modelling and experimental validation, it is demonstrated that the GM-based PVT collector reduces the PV panel temperature and compensates for the extra pressure drops, leading to higher overall system efficiency. A maximum of 25% total efficiency enhancement is observed for GM-based PVT collectors over flat plate PVT collectors. The optimal configuration involves a low airflow rate, a narrow air channel, and the largest available GM spikes. These findings contribute to developing cost-effective and efficient air-based PV/T collectors that can be integrated with HP-based systems to provide building heating load.</p>

Thermal projects are gaining popularity in the solar energy research community owing to their substantial energy storage density and efficiency in converting energy. Solar thermal collectors are technologies made to capture solar radiation and convert it into thermal energy. Solar collectors and storage mechanisms for thermal energy are the two main aspects in the aforementioned uses. Static solar thermal collectors use basic design concepts to efficiently collect, store, and transport solar heat in order to harvest solar energy. This research paper focuses on the most recent advancements and achievements in solar thermal utilisation, covering an assessment of solar collectors and thermal energy-storing systems. Thermal scenarios and the production of electricity from radiation from the sun are quickly evolving as the globe seeks future energy sources other than conventional ones. Solar thermal collectors are one of the most basic requirements for converting the solar energy into usable forms.

Photovoltaic-thermal (PVT) collectors combine photovoltaic modules and solar thermal collectors, forming a single device that receives solar radiation and produces electricity and heat simultaneously. PVT collectors can produce more energy per unit surface area than side-by-side PV modules and solar thermal collectors. There are two types of liquid-type flat-plate PVT collectors, depending on the existence of glass cover over PV module: glass-covered (glazed) PVT collectors, which produce relatively more thermal energy but have lower electrical yield, and uncovered (unglazed) PVT collectors, which have relatively lower thermal energy with somewhat higher electrical performance. In this paper, the experimental performance of two types of liquid-type PVT collectors, glazed and unglazed, was analyzed. The electrical and thermal performances of the PVT collectors were measured in outdoor conditions, and the results were compared. The results show that the thermal efficiency of the glazed PVT collector is higher than that of the unglazed PVT collector, but the unglazed collector had higher electrical efficiency than the glazed collector. The overall energy performance of the collectors was compared by combining the values of the average thermal and electrical efficiency.

Insulated concrete form foundation wall as solar thermal energy storage for Cold-Climate building heating system

The truck-mounted solar collector testing system is a flexible and convenient testing device. However design of thus a system is much more difficult than that of the fixed solar collector testing system, because it needs consideration in every respect so as to make sure the following: accurate testing, accommodation of the reduced volume of the testing system, stability of the testing system, addition of a removable device and so on. This article explores the systematic design of the truck-mounted solar collector testing system, points out the design issues to be considered, propose an appropriate design plan, and finally conducts the main force calculation. Solar energy is one of the cleanest sources; it is green and pollution-free. Today, environmental pollution is getting worse and worse; thus application of solar energy is becoming more extensive. A solar collector is defined as any of various devices that absorb the solar radiation and deliver the heat energy to the medium of heat transfer device. Solar collectors are not a direct consumer-oriented product, but key components that form various solar thermal systems, such as solar water heaters, solar energy dryers, solar industrial heaters and so on, of which the solar collectors are a core part of the system. At present solar heat pipe collectors and collector plates are the two most widely used products of solar collectors. Factory productions of such products are subject to inspection before they can be put on the market. Currently product testing of this kind is performed collectively in fixed locations; consequently, it is vulnerable to the geographical conditions, climate changes, and other factors in the location. A truck-mounted solar collector testing system is a system that integrates both testing systems, heat pipe collectors and collector plates, in a vehicle, which can be driven into the manufacturers that produce heat pipes and/or heat plates or other places where testing conditions can be met according to the requirements. By doing so, the problems associated with the fixed testing system can be solved. However, design of truck-mounted type solar collector testing system is much more difficult than that of fixed solar collector testing system. In addition to testing accuracy, it must also take the reduced volume of the testing system into account to ensure that the system can be accommodated into a smaller space of the vehicle. Furthermore, the stability of the testing system must be assured. Finally a removable device needs to be added to the system for convenience. In the following, we show our design of the truck-mounted solar collector testing system and calculations for the related stress analysis.

Thermal performance of flat plate solar collectors with sheet-and-tube and roll-bond absorbers