Solar energy conversion can be small-scale and low-tech

As one of the renewable green energy sources, solar energy has great advantages in energy conservation and environmental protection. With the deepening of the research on solar heating technology, more issues have been discussed. This paper summarizes the research status of solar heating technology from two aspects of solar energy heat collection and heating implementation. Firstly, heat collection technology is still the key to solar energy heat utilization, which focuses on the numerical simulation of heat collector and the influence of heat collection structure on heat collection capacity. Secondly, thermodynamic analysis of heat transfer enhancement of ventilation gap and air flow in passive solar heating system is a hot topic; some scholars even put forward new heat transfer theoretical models and improved equations. Whereas in the active solar heating system, due to the imbalance and instability of solar energy, most of the research focuses on the construction of multiple complementary heating system and the corresponding optimal operation mechanism as well as the study of solar energy heat storage materials, devices and their heat storage performance. Thirdly, in view of the actual building environment in rural areas of northern China, it is proposed that using distributed solar energy collection method combined with heat storage technology and using green energy internet to distribute heat energy is the research trend of maximizing the application of solar heating in the region.

Solar energy conversion is the one modern power supply technology in which small units appear feasible. Economics may dictate large plants when the heat source is conventional boilers or nuclear reactors, but, along with sunlight collectors half the size of Arizona, solar units small enough to power not more than a single house are a serious feature of most solar-energy proposals. This wide variation of scale makes a variety of local and individual initiative possible in solar conversion. It's not necessary to draw up plans for a multimegawatt interconnection to start. An example of such a local initiative is San Jose State University in California, which is engaged in a 15-year program to apply solar energy to various uses on its campus. By the end of that time the university expects to get between 30 and 50 percent of its total energy requirements from sunlight collected on the campus, Donald W Aitken, director of the University's Center for Solar Energy Applications, told the American Physical Society Meeting in San Francisco. The San Jose team started the project in 1975 by taking a campus map and coloring in yellow the places where solar energy might be applicable. They were surprised at how yellow the map became. They ordered the ensuing projects in a logical sequence. One of the first to be done was what Aitken calls the largest solar hot water system yet built in the United States. It provides 70 percent of the hot water needs of 600 students in three dormitories. Like most successful solar energy systems it can rely on other sources of energy for backup when the sun is overcast. The 70 percent is a weather hazard figure, Aitken says. On a sunny day, we don't use any gas. When he spoke, northern California had just been through an extended rainy period, during which solar energy did very little. But, if you notice that the sun came out in earnest yesterday and a little bit the day before, ... yesterday afternoon we were delivering 1400 water. The 9,000-square-foot-system is laid out on top of the three buildings it serves. It was built with $180,000 of state funds. We have yet to write a research proposal, Aitken says. If we're really going to argue that solar energy is an available, practical resource, we've got to put our own dollars where our mouths are. The system was built by students, illustrating both the pedagogical value of the program and the talent available in the student body for pursuing solar-energy conversion. The program envisions starting at least one major project a year. The next one in line is a new library. The library is designed to use the heat of human bodies and artificial lighting for space heat. When the days are too hot, the coolness of the night will be used to cool the building in the day. For times when bodies and lights do not suffice, the south wall of the building will incorporate a solar energy system for backup heating. This system adds $600,000 or $700,000 to a $10-million building, and is expected to pay itself back in five or six years. Aitken maintains that nowhere in the San Francisco Bay area should new construction have to rely on burning fossil fuels for space heating or climate control generally. After the library will come the conversion of the dining commons, which feeds 2,500 students a day. First, the wasted heat from over the stoves and from the dishwashers will be harnessed for space heating. So much heat is lost from stoves and dishwashers, says Aitken, that if it can be used, no restaurant need rely on any other source for heat. Then a solar unit to heat water for the dishwashers will be added. After the dining commons, the student union will get the treatment. Each project is different. Each takes into account the activities that go on in a given building and the advantages that can be drawn therefrom. None of the existing or immediately planned installations generates electricity, but the later stages of the program will include generation of 400,000 watts in electric power along with 2 million watts thermal plugged into the university's central boiler. Aitken insists that conversion projects of this kind are feasible not only in San Jose, which has a mild climate and lots of sunny weather, but in any part of the country including Seattle, Washington, and Maine. O Students installed collecting panels and tanks for solar-powered hot water system on roofs of dormitories at San Jose State.

When designing solar thermal collectors, non-stationary operating conditions of the solar system are considered to determine the instantaneous heat output and temperature of the heat carriers during a given day or period. It is known that the amount of useful heat absorbed by a solar thermal collector is directly dependent on the temperature of the heat carrier at the inlet and outlet of the solar thermal collector. The calculation of the heat consumption and/or storage system also requires the temperature of the heat carrier at the outlet of the solar collector. The heating of the heat carrier in a solar collector can be divided into two stages: heating of the walls of the heat exchanger (cylindrical channel) in a solar thermal collector by solar energy and heating of propylene glycol/ethylene glycol in the heat exchanger (cylindrical channel) of a solar thermal collector. This paper presents seven methods for determining the temperature field of the walls of the heat exchanger (cylindrical channel) of a solar thermal collector, depending on the initial and boundary conditions. The most general case for calculating the temperature field of propylene glycol/ethylene glycol moving in the heat exchanger of a solar heat collector assumes the presence of heat exchange on the surfaces of its contact with the walls of the cylindrical channel and with the environment. The calculation takes into account the difficulties associated with the significant nonlinearity of boundary conditions of the "given surface radiation" type. That is, it is taken into account that one surface of the heat exchanger channel is turned to solar radiation, and the opposite is turned to the back wall of the solar heat collector. The solution is found analytically using the method of Green's functions.

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.

Electricity-assisted thermochemical sorption system for seasonal solar energy storage

Economics of small solar-assisted multiple-effect stack distillation plants

State-of-the-art review on water-based nanofluids for low temperature solar thermal collector application

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.

Dairy farming has become a key business to fulfill the daily milk needs in populated countries like India. Conversely, pathogenic and spoilage microorganisms in raw milk are killed by applying different heat treatments to increase shelf life, preserve quality, and ensure safety. Among the heat treatment processes used at the dairy plant, pasteurization consumes a significant amount of heat, which increases the energy demand in the dairy sector. Since milk pasteurization occurs between 65°C and 150°C, multiple solar thermal collector alternatives are available for various kinds of pasteurization processes. Employing solar thermal collectors for milk pasteurization allows the dairy sector to use free solar energy. Solar energy in milk heat treatments minimizes fuel and power consumption, reducing carbon emissions and promoting sustainability. However, solar milk pasteurization in dairy sector is limited by the large area requirement, high initial cost, and weather dependency. There have been attempts to use different types of solar thermal collectors to pasteurize the milk in an effort to replace conventional energy usage with solar energy. The parameters of milk heat treatment, primarily pasteurization, have been discussed concerning energy usage. The benefits and limitations of various solar collectors for milk pasteurization and other heating applications in the dairy sector have been addressed. Multiple studies on integrating various solar thermal collectors with different pasteurization systems have been reviewed, summarized, and concluded.

The demand for cooling in Gulf region is the direct effect of its high atmospheric temperature. Around 60% of the electricity demand in GCC is for cooling purpose. The main source of cooling and air-conditioning in these countries are conventional electric compression cycle, which leads to the increase in the GHG emission, directly in the form of leaked gases from these systems and indirectly in the form of fossil fuel used for the production of the used electricity for these systems. Solar energy in general and solar thermal energy specifically can be a promising and sustainable solution to the cooling and air-conditioning requirement for the buildings in Qatar and GCC. Absorption cooling and air-conditioning is a mature and promising technology with respect to its efficiency and results on the industrial scale. However, the use of technology with solar thermal energy is new in the market. In this paper, the feasibility analysis of solar thermal technology has been done for the cooling, heating and hot water requirement of a commercial building in Doha, Qatar. Heating and hot water requirement for winter and cooling requirement for summer season were calculated and used as a load. Solar thermal collectors (STC) were used as the main source of thermal energy collection form sunlight. Along with STC, thermally driven adsorption chiller was designed to fulfill the cooling requirement in the summer season. The design and selection of the different components and parameters such as Solar thermal collector area, storage tank size, adsorption chiller etc. have been done in detail. The result, obtained for building's energy demand and its supply from the designed solar thermal system, gives a clear sign for the successful implementation of this technology.

With the development of rural economy, energy demand is also growing, in order to solve the problem of rural energy, ecological villages and towns should establish a point of view, focusing on the development of renewable energy. Solar energy is very rich in renewable energy, pollution-free environment. Solar energy is more and more important to people, so and the technology of solar energy. For the study to the rural areas of North China, Paper analyzing the feasibility of popularizing solar heating in countryside from the advantage of solar heating, the advantage of solar heating in countryside and the system of solar heating, At the same time, we study the key technologies of solar heating, such as the choice of collector, the choice of the thermal storage tank volume. It shows that there is a great value and significance promoting solar heating in countryside, especially solar radiant floor heating. Popularizing the use of solar heating can reduce greenhouse gas emissions and pollutant emissions of conventional energy use, minimizing burden of rural heating, it is clean, health, safety, meeting the objective requirements of the new rural construction. In the new rural construction, solar heating has better social benefits and promotion prospects; there is a positive role in promoting China’s economic, environmental and energy construction.

Experimental and numerical study on a freeze protection system for flat-plate solar collectors with silicone peroxide tubes

Research and application of park multi-source synergistic and complementary heating system and its coordinated control method

The intermittent nature of solar energy is a dominant factor in exploring well-designed thermal energy storages for consistent operation of solar thermal-powered vapor absorption systems. Thermal energy storage acts as a buffer and moderator between solar thermal collectors and generators of absorption chillers and significantly improves the system performance. Vapor absorption chillers are available in half, single, double, and triple-effect modes of operation and operate at temperatures ranging from 75 to 220°C to produce a cooling effect with COPs ranging from 0.3 to 1.8. Thus, the selection of appropriate solar collectors and thermal energy storages are two significant decisions affecting the consistency of output of a vapor absorption refrigeration system. The present review of state of the art is focused on the appropriate selection, from among different types of solar collectors available to meet the demand of capacity and degree of thermal energy required in operating absorption chillers at optimum performance. Characteristics of various thermal energy storage systems and their integration with solar thermal collectors and absorption chillers are also investigated to meet the demand for heat during non-sunshine hours or periods of low solar intensity. In the latter section, economic feasibility is explored so that a sustainable solar cooling system can be proposed which can work consistently with the best performance throughout its entire life.

Objectives: The objective of the current work is to demonstrate Liquid desiccant based air conditioning (LDAC) systems to reduce energy consumption and cater to latent cooling load more effectively. Methods/Statistical Analysis: This work describes three different projects undertaken to demonstrate efficacy of LDAC systems. One of the project demonstrated regeneration of liquid desiccant in a simple but economical solar thermal collector along with integrated liquid desiccant (LD) heat exchanger. Two other projects demonstrated regeneration using waste heat source and dehumidification of air in an internally cooled LD-air contacting device. Experiments were carried out in city of Vadodara in summer months of year2017 and encouraging results are found. Findings: The passive solar regeneration project showed that a latent cooling rate of 96 W can be provided using an LDAC system per m2 area of solar thermal collector. Another useful utility in form of distilled water could be produced at a rate of 1.7 liters in a day per m2 area in this collector. The internally heated device used for demonstrating use of waste heat for LD regeneration could provide moisture removal rate of around 3.0 kg/h from air using aqueous solution of calcium chloride as LD with an average concentration of 37.7%.In the internally cooled air-LD contacting device, 2.0 kW of latent cooling along with 0.3 kW sensible cooling could be provided for air entering at around 34.7o C temperature and 47.5% relative humidity with an average chilled water temperature of 9.5o C and LD concentration of 40.0%. These experiments have thus demonstrated and established efficacy of LDAC system to provide effective dehumidification with use of energy sources with nominal recurring costs and reduced pollutant emission. Application/ Improvements: Reducing heat losses in solar collector, air bypasses in the contacting device and higher residence time of LD in contacting device can help improve these results further. Keywords: Air Conditioning, Dehumidification, Energy Conservation, Liquid Desiccant, Solar Energy, Waste Heat