Use Of Solar Heat Research Articles

Experimental Analyses on Feasibility of Chemical‐Looping CoO/CoAl2O4 with Additive for Solar Thermal Fuel Production

AbstractSolar thermal fuel production from solar heat is considered an innovative technology for the utilization of solar energy. The process of solar‐heat‐driven hydrocarbon fuel reformation is a promising approach for solar thermal fuel production. Here, perspectives on the use of solar heat at approximately 673–723 K to drive dimethyl ether (DME) reformation with a looping material of (CoO+1.0 % PtO2)/CoAl2O4 are given for the production of solar thermal fuel, and the experimental results for the thermochemical reactivity and the stability of this looping material are discussed in particular. The experimental results indicate that the synthesized (CoO+1.0 % PtO2)/CoAl2O4 shows good reactivity at a solar thermal fuel production temperature of 673–723 K, at which the conversion rate is 80–95 %. Moreover, the looping material also shows a satisfactory stable redox stability over 16 cycles. To avoid the deactivation of the looping material by carbon deposition, H2O is introduced to accompany the solar‐driven reduction of (CoO+1.0 % PtO2)/CoAl2O4 with DME. Although the PtO2 additive is expensive and not “ideal”, the results obtained in this study may provide a starting point for solar thermal fuel production from mid‐temperature solar heat using the chemical‐looping combustion of DME.

Integration of a solar thermal system in a medium-sized brewery using pinch analysis: Methodology and case study

In the food industry a major portion of thermal energy is required for low temperature applications (below 100°C). As a consequence, there is a significant potential to substitute fossil fuels by the use of solar heat. This paper presents a methodology that first uses pinch analysis to optimize a medium-sized Scottish brewery from a direct heat recovery perspective followed by the integration of a solar thermal system. Both the time average model and time slice model were used to determine direct and indirect heat recovery potentials. In a second stage, an optimization of a chosen integration point was conducted to assess the viability of the resulting design concept. The economic analysis includes an assessment of the impact of restrictions in the UK government’s Renewable Heat Incentive program. It was determined that since solar thermal systems are financially supported up to an installed capacity of 200kW, solar heat can only account for a maximum of 7.7% of the heat demand based on the investigated brewery. However, if there was no limitation in capacity, from an economic point of view, the solar fraction could almost be doubled drawing into question the need for the restriction. Nevertheless, a CO2 saving potential of approximately 38tons per year in conjunction with a payback period of 6.4years was determined.

Progress towards a more sustainable synthetic pathway to ibuprofen through the use of solar heating

The ACS Green Chemistry Institute Pharmaceutical Roundtable was formed in 2005 to encourage the incorporation of green chemistry techniques into the synthetic pathways of pharmaceuticals. Through this initiative, synthetic pathways of several pharmaceuticals have been altered to adapt more environmentally friendly procedures. The amount of electricity required to complete chemical reactions have become an environmental concern due to depleting fossil fuels. A technique was recently developed in which satellite dishes were repurposed as solar reflectors capable of providing a heat source through solar irradiation. The ability to use the solar reflector as the sole heat source for synthetic reactions has been analyzed for the commercially important pharmaceutical, ibuprofen. Ibuprofen synthesis also incorporates chemicals that are not particularly friendly to the environment. The exchange of these chemicals with more environmentally friendly substitutes has been analyzed. The goal of this study is to incorporate a solar energy heat source to develop an alternative energy, more environmentally friendly pathway to ibuprofen.

A Simplified LCA Tool for Solar Heating and Cooling Systems

This paper presents a user-friendly Life Cycle Assessment tool, which aims to support researchers, designers and decision-makers in evaluating the life cycle energy and environmental advantages related to the use of solar heating and cooling (SHC) systems in substitution of conventional ones, considering specific climatic conditions and building loads.The tool was developed within the Task 48 “Quality Assurance & Support Measures for Solar Cooling Systems”, promoted by the International Energy Agency in the framework of the SHC Programme.

Solar-Combined Thermoelectric Power Generation Simulator

Photovolatic (PV) devices are gaining popularity in harnessing solar energy as a form of sustainable renewable source to generate electricity. However, these devices are limited to utilizing only high energy photons (UV and visible) from the solar spectrum which curtails their efficiency restricting them from being employed in large-scale power generation. This study explores ways to tap into the wasted wavelengths of the spectrum by adding a thermoelectric (TE) module and a steam turbine cycle to the system in hopes of improving power output and thus overall efficiency. The TE device makes use of solar heat to develop a temperature gradient which through the Seebeck effect will later be used to produce electricity. A steam-driven Rankine cycle through a heat exchanger will connect to thermal storage as well as a mechanical engine. This storage will allow for dispatchability at a modest cost. The simulation tool built allows to compute expected power output and efficiency at each individual stage of the combined system. The user is at liberty to manipulate parameters such as concentration of the solar selective absorber and material properties of the TE and PV modules. Test runs indicate that the overall efficiency of power generation has increased by the combined system. This system can be used as a basis for future models in large-scale energy production. KEYWORDS Solar-Energy, Photovoltaic, Thermoelectric, Efficiency, Purdue University REFERENCES Bell, L. (2008, September 12). Cooling, heating, generating power, and recovering waste heat with thermoelectric systems. Science, 321, 1457-1461 Gray, J., & Wilcox, J. The design of multijunction photovoltaic systems for realistic operating conditions. Yazawa, K., & Shakouri, A. (2011, July 27). Cost-efficiency trade-off and the design of thermoelectric power generators. Environmental Science & Technology, 45, 7548-7553.

Decision Support for the Construction of Farm-Scale Biogas Digesters in Developing Countries with Cold Seasons

Biogas production is a clean renewable energy source that can improve lives in developing countries. However, winter temperatures in some areas are too low to enable enough biogas production in small unheated digesters to meet the energy requirements of households. Low-cost, high yield reactors adapted to the local climate are needed in those situations. A decision-support model was developed to assist in the design of biogas reactors capable of meeting households’ year-round energy needs. Monthly biogas production relative to household energy needs was calculated for the scenario of suburban Hanoi, Vietnam. Calculations included pig number, slurry (manure water mixture) dilution, retention time and biogas/solar heating. Although using biogas to heat the digester increased biogas production, it did not lead to an energy surplus, particularly with the 1:9 slurry dilution rate commonly used on pig farms. However, at a 1:3 slurry dilution, the use of solar heating to provide 90% and biogas 10% of the heat required to heat the digester to 35 °C improved the biogas production by 50% compared to psychrophilic production. The energy needs of an average five-person family throughout the year required 17 fattening pigs. This model can establish the best solution for producing sufficient energy throughout the year.

Low-cost small scale processing technologies for production applications in various environments—Mass produced factories

The requirements for chemical and food production technologies will change in the future as a result of shorter time to market and increasing market volatility. Especially the rising use of renewable resources will require the implementation of flexible and fast to install small-scale production technologies. The increasing number of necessary apparatuses and their distributed operation, however, will constitute major challenges, both economically and procedurally. The proposed solution to face the economic challenge is modularization and standardization. For food production, dewatering represents a key issue. Thus, biomass processing should first be divided into small-scale water separation steps and then into further large-scale processing steps. As dewatering usually happens thermally and heat exchangers often benefit from the economies of scale, heat supply and energy consumption or heat transfer with little capital investment are further issues. Therefore, temperature levels should be decreased and the use of solar heat increased. For the production of biofuels and chemicals from biomass, process integration and process simplification are proposed to improve the efficacy of production equipment and processes. Choosing raw materials with molecular structures, similar to the desired chemical building block, will lower the need for heat exchange and make small-scale manufacturing of fuels and chemicals possible.

Soft ground improvement with solar-powered drainage

In this study, raising the temperature of soft Bangkok clay up to 90°C using solar-powered prefabricated vertical drains during a preloading process was investigated in full-scale field tests. Two identical 6 m high, full-scale test embankments for preloading were constructed over the soft Bangkok clay where a conventional vertical drainage system was installed underneath one embankment and a solar-powered system was utilised for the other. Analyses were carried out to determine the flow parameters by back-calculation of field settlements in terms of the horizontal coefficient of consolidation (Ch) and the ratio between the horizontal hydraulic conductivity in the undisturbed zone (Kh) to the horizontal hydraulic conductivity in the smear zone (Ks). The field test analysis based upon the back-calculated results shows that the Kh/Ks values were 6·2 and 4·1 for drainage without and with heat, respectively, with corresponding Ch values of 6·8 and 8·5 m2/year, respectively. Thus, the use of solar heating can increase the drainage performance by reducing the drainage retardation effects in the smear zone around the drain.

Review: Greenhouse Solutions with Sustainable Energy

Review: Greenhouse Solutions with Sustainable Energy By Mark Diesendorf Reviewed by Elery Hamilton-Smith Charles Sturt University, Australia Diesendorf, Mark. Greenhouse Solutions with Sustainable Energy. Sydney, NSW: University of New South Wales Press, 2007. 413 pp. ISBN 978-086-8409-733. AU$45.95, paper. This is indeed a timely book. The proliferation of books on world environmental trends, policies and issues means that there are literally thousands of pages clamoring for the attention of those interested. Many of these are simply advocating specific conceptualizations and solutions to one or more of the many global problems. Too many of them either neglect, or are deficient on, critical assessment of the necessary evidence. Diesendorf writes with great clarity, explaining complex issues and ideas without over-simplifying or dumbing down. Essentially, after a basic conceptual review, he critically evaluates eight major strategic directions, either already practiced or commonly proposed and advocated in global policy arenas. Each of these strategies is assessed in terms of the potential resources, current status and action, environmental, health and social impacts, economic and future development potential. Essentially, he concludes that, at least in Australia and probably globally, a combination of efficient energy use, solar hot water, gas, bio-energy, wind power, improved public transport and fuel-efficient vehicles could halve greenhouse emissions within a few decades. But the political will is lacking, and much government policy action serves only to further the production of greenhouse emissions. The large and wealthy fossil fuel industries, including their infrastructural demands such as power stations, transport, urban structure and building standards, are major determinants of governmental expenditure. The whole situation is compounded by neo-liberalist politics which largely leaves long- term planning in the hands of the market, which in turn is dominated by the same big greenhouse industries. The first of the strategies examined is efficient use of energy – virtually self-evident, yet outdated and inappropriate practices are allowed to continue unthinkingly. Hand-in-hand, and increasingly accepted, the effective development of wind energy has made immense strides and very significant savings. At the same time, there are constant negative responses to increased wind power often supported by gross untruths and deliberate falsehoods. Bio-fuels production and utilization again are effective and efficient strategies. The use of solar heat and energy is clearly effective and, in the long run, efficient. Further research and development is under way, and in due course, this will deliver greatly improved systems of technology and management. Other appropriate energy technologies are also being developed – marine and hydropower, geothermal heat and energy, and enhanced energy storage systems. One of the major problems lies in the urban form and the transport industries. Both are responsible for a large number of other damaging impacts upon human health and the environment. There have been a number of positive innovations by automobile manufacturers, cyclists and others. Again, governmental policies fall far behind the front line of action. Coal remains the major source of problems, and probably will continue to do so for a very long time. This is discussed in a chapter titled “Coal and Gas: Can we bury the problem?” Although considerable claims have been made in relation to geo-sequestration, and there is considerable investment in research and experiment, the prospects do not appear very strong. Moreover, burying the emissions does nothing about the other widespread impacts which arise from the use of coal.

Rate of Loss of Simazine, Terbuthylazine, Isoproturon, and Methabenzthiazuron during Soil Solarization

This paper reports the use of solar heating by polyethylene mulching for decontamination of a silty clay-loam soil polluted with herbicides. Soil solarization, a natural and hydrothermal method commonly used for disinfesting soils, was tested during the summer season on a Hipercalcic Calcisol located in Murcia (southeast Spain) for dissipation of s-triazine (simazine and terbuthylazine) and phenylurea (isoproturon and methabenzthiazuron) herbicides using low-density (LD) and high-density (HD) polyethylene (PE) film as a cover. A well-established influence of the film was observed on the dissipation of all herbicides from the soil, although the density (0.92-0.95 g/cm(3)) of the film used (LDPE and HDPE) was not significant in terms of the rate of loss. In all cases, a quick depletion during the first 2 weeks was observed, mainly for terbuthylazine. The first-order model satisfactorily explained the dissipation process, but the Hoerl and biexponential equations were more appropriate, mainly for simazine, isoproturon, and methabenzthiazuron. In all cases, herbicides disappeared at faster rates in solarized soils (DT(50) = 4-29 days) than in nonmulched soils (DT(50) = 11-35 days), especially for terbuthylazine and isoproturon.

Energy conservation effect of new HVAC system for condominiums with solar collectors integrated with the balcony handrail

Energy consumption in Japan's houses has been increasing rapidly over the past decades. Furthermore, installation of 24-h ventilation systems in houses became mandatory last year, which will probably increase the heating, ventilation, and air conditioning (HVAC) energy consumption in Japan's houses. Regardless of these situations, natural energy utilization to reduce HVAC energy has not spread, especially in condominiums in Japan. In this study, we propose a new HVAC system for condominiums that makes use of solar heat, outdoor cool air by integrating elements in condominiums such as the balcony handrail, the 24-h ventilation system, and under-floor space. As a first step in the development of this system, we carried out experiments and computational fluid dynamics (CFD) studies on a solar heat collector integrated with the balcony handrail to determine its specification and to obtain information on its heat collection performance. As a second step, we calculated dynamic thermal load on a model condominium to evaluate the energy-saving performance and thermal comfort of the proposed system. The calculation results show that the proposed system has a high performance, both for energy saving and thermal comfort.

An Efficient Method for Assessing the Quality of Large Solar Irradiance Datasets

There has been an enormous increase in the use of solar heating and photovoltaic systems worldwide. Building professionals to better design buildings, windows and other solar related constructs require current and accurate compilations of solar irradiance data. Frequently, enough care is not exercised with respect to quality of the measurements. Traditionally, researchers have used several methods for the quality assessment of solar irradiance data. This article addresses two of those methods, visual and quartile analysis, often used to identify “outliers” in the large datasets typically found in solar energy related research. The present work introduces another method for identification of erroneous data, based on standard deviations, using the clearness index and the diffuse ratio. This method is highly efficient in terms of its algorithmic approach.

FUTURE RESEARCH ACTIONS IN PASSIVE COOLING

The PASCOOL program was the most important European project on passive cooling of buildings. The project addressed topics included solar control, the combined effect of ventilation and thermal mass, thermal comfort during summer and the potential of natural cooling techniques. PASCOOL put in evidence also the axes towards which future research on passive cooling should be oriented. This research, giving the continuously increasing trend of energy consumption for cooling purposes, is absolutely necessary in order to take advantage of the complete potential that passive cooling can offer to buildings while maintaining the living standards, health and comfort of the occupants. This paper presents these future issues that comprise (a) research on the microclimatic scale in order to address the impact of outdoor environment on the cooling load of buildings, (b) investigation of comfort requirements under transient conditions during summer, (c) research on natural ventilation in urban environments and the impact of outdoor pollution on indoor air quality, (d) development of alternative cooling systems and techniques, (e) development of integrating design concepts optimising the use of solar heating, passive cooling and natural light in buildings.

Use of solar heat to upgrade biogas plant performance

The performance of a biogas plant is temperature dependent. At higher temperatures specific gas yield rises almost linearly with temperature and throughput time is reduced. In winter, gas yield drops due to a fall in temperature of the slurry. In winter, if slurry could be heated to 50°C, more efficient operation in the thermophilic range would be possible. The source for heating the slurry has to satisfy many constraints: year-round supply at low temperatures and should have no fuel costs. A salt gradient solar pond satisfies these criteria. The heat transfer system should avoid hot spots above 55°C but ensure effective performance. A temperature above 55°C will destroy methanogenic bacteria. A vapour condensation heat transfer system based on acetone (b.p. 55°C) consisting of a sealed system in which two containers, one each in a biogas digester and solar pond, connected by a sloping pipe is suggested.

A survey of solar energy utilization in Finland

SYNOPSIS Biomass is the most important indigenous energy source in Finland and its share of the primary energy consumption was about 16% in 1982. Its significance in the future has also been recognized by the government's energy policy. The use of solar heating for buildings is mainly limited to experimental projects. The gross technical potential of solar heating after the turn of the century was estimated to be 4.8 Mt o.e. (5.4 TWh).

Analysis and performance of a V‐trough solar concentrator

AbstractA thermal analysis of the V‐trough solar concentrator for use in solar heating and cooling is presented. A compact analytical expression for estimating Solar Insolation received by a collector for any day with any sky conditions has been formulated. The estimated values are found to be very close to quantities recorded by solar radiation measuring instruments. The V‐trough concentrator was investigated experimentally and found to be more efficient than a flat plate collector. It provided temperatures higher than 90°C. It is thus more suitable to utilize in absorption refrigeration applications.

Canada''s Solar Demonstration Programs: Results And Implications For the Future

Introduction While many may think that Canada is too far north, and too cold a country to hope to have any realistic solar energy potential, it has in fact been in the solar business for many years. In spite of the fact that Canada is rich in many natural resources, there is a clear commitment to develop its renewable energy resources, including solar energy. Renewable energy, excluding hydro-electricity, contributes currently about four per cent of Canada's energy supply. This amounts to about 400 PJ of energy and comes from previously photo synthetically captured solar energy: bio-energy. The combustion of wood residues by the Canadian forest industry and the use of firewood for residential space heating have increased dramatically during the last few years. The direct solar potential in Canada is quite large. Solar radiation levels in several areas of the country match those in the southern U.S.A. The potential for solar energy was recognized over a decade ago when an R&D effort was initiated by the National Research Council. The primary emphasis was directed in solar thermal through the development of solar collectors. Other areas such as passive solar and photovoltaics have also been pursued. This paper concentrates on Canada's past developments and its future programs in active solar energy. Previous Programs Major efforts in active solar thermal energy really picked up in 1978 when, largely in response to rapidly-increasing world oil prices, programs were instituted tQ increase solar R&D funding, develop a solar manufacturing industry, provide a market for this industry's products, and demonstrate solar applications to the public. Nearly half of Canada's (with government and industry) expenditures on solar energy development over the past five years has been on research and development. Approximately 80 to 90% of the government's outlay for this work is contracted out to private industry. Only a small in-house staff is used to manage these contracts and do some limited laboratory work. This is consistent with over-all Canadian federal policy of contracting Out scientific research and development needs:product and industrial development andsystem trials with monitoring and analysis. Among the many accomplishments in this area is the creation of one of the most advanced solar certification centres in the world-the National Solar Test Facility, operated under the auspices of the NRC near Toronto, Ontario. In 1978 a program known as PASEM (Program of Assistance to Solar Energy Manufacturers) gave grants totalling Over $4 million to a selected group of ten companies to basically set up a manufacturing capability for solar energy products. A follow-on program to that one was then introduced: PUSH (Purchase and Use of Solar Heating), where the federal government procured and installed active solar heating systems on federally-owned buildings across Canada. This provided a ready market for the fledgling solar industry and accepted the high, initial risk associated with the as yet, untried products. Other programs also were set up to subsidize the initial cost of active solar systems used by the private and commercial/ industrial sectors.

Optimal Control of Solar Heating and Off-Peak Energy Storage Installations

It is well known that the widespread use of solar heating or cooling systems could lead to an increase in the cost of supply of power by the electric utilities. However, it is also recognized that by using appropriate control strategies in these systems the cost of supply may be reduced relative to that of electric resistance heating systems. Control strategies for solar heating systems and for off-peak heat storage systems have been developed and investigated in terms of utility cost of supply for the year 1990. This paper includes a discussion of results obtained for off-peak storage systems, solar heating systems, and combined solar and off-peak systems for the area served by Public Service Co. of New Mexico.

Modern trends in heat pump development

Modern trends in heat pump development are discussed. Motor/compressor units are now being designed specifically for heat pumps. The use of solar heat, direct fired domestic heat pumps (eg with natural gas), the Stirling engine and Rankine cycle heat pump are being investigated.

First-Order Design Variables For Concentrating Solar Collectors

Solar flux is inherently of very high thermodynamic quality (low entropy). However, the terrestrial use of solar heat at high temperature can be achieved only by means of solar concentrators of the reflecting or refracting type. It is the purpose of this paper to describe the three major design variables of concentrators optical efficiency, heat loss coefficient and heat removal factor. The optical efficiency no embodies many important concentrator properties including mirror surface reflectance and slope, tracking accuracy, receiver transmittance and adsorptance and solar beam incidence angle effects. The heat loss coefficient Uc of a solar concentrator represents its thermal performance and depends upon the relative magnitudes of convection and conduction flux rates, surface emittances of receiver components and operating temperature relative to the environment. The third design parameter-the heat removal factor FR-is a measure of the efficiency of the receiver when viewed as a heat exchanger. Its value is governed by working fluid properties and flow rates as well as by the thermal properties of the receiver material. The principal factors which determine the value of no, Uc and FR are described in the paper.