Active Solar Collectors Research Articles

EXPERIMENTAL INVESTIGATION OF INDIVIDUAL EVACUATED TUBE HEAT PIPE SOLAR WATER HEATING SYSTEMS

lar water heating systems with heat pipes of three diameter groups of 16, 22 and 28.5 mm. The first and third groups had evaporator lengths of 1150, 1300 and 1550 mm. The second group had an additional length of 1800 mm. all heat pipes were of fixed condenser length of 200 mm. Ethanol at 50% fill charge ratio of the evaporator volume was used as the heat pipes working fluid. Each heat pipe condenser section was inserted in a storage tank and the evaporator section inserted into an evacuated glass tube of the Owens- Illinois type. The combined heat pipe and evacuated glass tube form an active solar collector of a unique design.The resulting ten solar water heating systems were tested outdoors under the meteorological conditions of Baghdad, Iraq. Experiments were carried out with no load, intermittent and continuous load conditions. Some tests, at no load, were carried out with and without reflectors. The overall system efficiency was found to improve with load conditions by a maximum of 55%. The system employing an 1800 mm evaporator length and 22 mm heat pipe (HP7) showed the best performance by higher water temperatures, overall useful energy gain and efficiency at various load conditions. System performance was predicted theoretically using electrical analogy derived from an energy balance. An agreement of within 14% was obtained between theoretical and experimental values.

Active solar collector located on roof ridge assisted Chinese solar greenhouse for thermal environment enhancement

ABSTRACT Maximizing the use of solar energy to increase the indoor temperature of greenhouse is of great significance to the green and energy-saving intensive greenhouse production in China. In this study, an active solar heating system (ASHS) was developed and analyzed, consisting of five solar water heaters equipped with vacuum tube solar collectors, one heat storage tank and heating system including booster pump and heating pipes. During the day, the water was heated in the solar collectors and stored in tanks before being placed into circulation in the heating pipes to distribute the heat to the aerial and root zones of plants. To evaluate the performance of ASHS and the feasibility of practical application, climate and plant growth parameters were monitored in two Chinese Solar Greenhouses (CSGs) located in Yangling, China. Results revealed that under the operating condition with the flow rate of 5.4 L/min, the effective heat collection, average heat collection efficiency and energy-saving efficiency of ASHS were 1.9 MJ/(m2•h), 64% and 84%, respectively. The coefficient of performance (COP) was between 4.5 and 6.2, and the payback period was 12.0 years. Furthermore, the results revealed that the ASHS successfully provided 76% of its annual heating needs, heated the CSG for 4 months and maintained the nocturnal temperature above 8 ℃. The actual application effect proved that it increased average indoor air temperature by 2.2 ℃ and substrate temperature by 3.3 ℃ in heated greenhouse. The growth rate of tomato plant height in the heated greenhouse was 0.7427 cm/d, greater than that in the unheated greenhouse (0.6 cm/d). The novel system proposed in this study adopting particular location enables the rise of the ambient and the substrate temperatures with lower energy consumption, improvement of the environmental conditions in CSG, and a more suitable growing environment for plants in the cold season.

Solar Access Assessment in Semi-Arid Urban Context: An Application Study for Ten Urban Forms of Existing Apartment Buildings Districts in Batna City, Algeria

The building sector has become one of the largest energy consumers in developing countries and should be considered a significant target for implemented energy-saving initiatives. The use of renewable energy, especially solar energy, could significantly reduce the dependence on fossil fuels. This paper analyzes the relationship between urban morphology and solar availability under the semi-arid climate and environmental conditions of Batna city (Algeria). A Grasshopper-based automated morphology generation and simulation system for evaluating solar access has been developed. Morphological and solar analyses of ten representative residential fabrics of Banta's collective housing stock were performed to compare and identify the best configuration in terms of solar technology use. Four solar performance indicators have been assessed: (i) Building Integrated Photovoltaic Index (BIPVi), (ii) Active Solar Collector index (ASCi), (iii) Passive Solar Index for Heating (PSI_heating), and (vi) Passive Solar Index for Cooling (PSI_cooling). Findings suggest that roofs receive three times more annual solar irradiation than facades and about four times more in Summer. Moreover, Samples showing consistent building height, low volume-to-area ratio, low site coverage, low density, and detached configuration get the best results of solar performance indicators. Finally, active solar collectors appear to be the most effective solar technology in the studied context.

Thermal behavior of asphalt pavement as an active solar collector under Malaysia climate condition using rubber tube

Thermal behavior of asphalt pavement as an active solar collector under Malaysia climate condition using rubber tube

Overview and analysis of current BIPV products: new criteria for supporting the technological transfer in the building sector

<p>The growing demand for nearly-Zero Energy Buildings is rapidly contributing to change the building skin from being a passive barrier towards a sensitive and active interface. Building Integrated Photovoltaics (BIPV) is a unique solution for delivering clean, safe, affordable and decentralized electricity to people transforming the building surfaces in active solar collectors. Despite photovoltaic (PV) technology and their basic usage are today known to everybody, the particular requirements for building integration have brought to the surface some issues over the years so that BIPV is still a niche market. Starting from this observation, the paper presents the results of an investigation on the current market of BIPV products for roofs and façade. The analysis aimed to identify the relevant possibilities the products today offer and the level of information that the producers make available within the technical description of BIPV systems. After disclosing the actual lack of information in comparison to conventional building products, the authors propose to implement a new “building-based” approach that could support the BIPV market by including a more comprehensive description of the product’s quality (today mainly comprising electrical and basic physical features). Such a “building-technology” perspective, also considering the recent normative framework in BIPV field, is expected to encourage the technological transfer of PV in the building sector by facilitating the daily work of architects, installers and the whole value chain.</p>

Thermal and hydraulic analysis of multilayered asphalt pavements as active solar collectors

The fulfillment of current environmental aims like reducing fossil fuel consumption or greenhouse gas emissions entails the development of new technologies that enable the use of cleaner, cheaper and renewable energies. Furthermore, the need to improve energy efficiency in buildings encourages scientists and engineers to find new ways of harvesting energy for later uses.The use of asphalt pavements as active solar collectors is introduced in this article. Several authors have studied the use of roads as an energy source before. However, a new technology is presented in which a multilayered pavement with a highly porous middle layer is used instead of a solar collector with an embedded pipe network. These collectors are fully integrated within the road infrastructure and may offer low cost solar energy for water heating.The paper includes a brief comment on the state-of-the-art. Then, a broad methodology is presented in which data, materials and procedures needed to run the tests are fully described. Finally, the results of the laboratory tests are stated and discussed.The prototype used in the laboratory provided excellent thermal efficiency. However, these good results contrast with the low flow rate levels registered during the tests. Thus, although this technology seems to be very promising, new experimental tests should be performed before an effective application is possible.

Design, modelling and computational assessment of passive and active solar collectors for thermal conditioning of the first bioclimatic hospital in Argentina

In this study, the design, modelling and computational simulation of solar air heaters installed at the first bioclimatic hospital of Argentina are presented, with details of the materials and dimensions of passive (Trombe walls and windows for solar direct gain) and active (solar air heaters of vee-corrugated black metal plates) devices. The building's thermal behaviour simulation was performed by means of Simulación de Edificios (SIMEDIF), a transient building simulation computational code developed at Instituto de Investigaciones en Energía No Convencional (INENCO). In order to determine the solar air heaters' collection area necessary to produce the energy required by each sector to be heated in the building, a simulation computational code was developed. The building is located in Susques, in the northwest of Argentina, at 3675 m over sea level, a region of very cold and dry climate. According to the simulations, the average daily indoor temperature in winter is 18°C whereas the average daily outdoor temperature is 2.5°C.

Renewable energy for passive house heating: II. Model

The evaluation of renewable energy used to increase the environmental friendliness of passive houses (PH) is the topic of this paper. A time-dependent model of passive house thermal behavior is developed. The heat-transfer through the high thermal inertia elements is analyzed by using a 1D time-dependent conduction heat-transfer equation that is solved numerically by using a standard Netlib solver (PDECHEB). Appropriate models for the conduction through the low thermal inertia elements are used, as well as a simple approach of the solar radiation transmission through the windows. The model takes into account in a detailed fashion the internal heat sources. Also, the operation of ventilation/heating system is described and common practice control strategies are implemented. Three renewable energy sources are considered. First, there is the passive solar heating due to the large window on the façade oriented south. Second, the active solar collectors system provides thermal energy for space heating or hot domestic water preparation. Third, a ground heat exchanger (GHE) increases the fresh air temperature during the cold season. The model was applied to the Pirmasens Passive House (Rhineland Palatinate, Germany). The passive solar heating system provides most part of the heating energy during November, December, February and March while in January the ground heat exchanger is the most important renewable energy source. January and February require use of additional conventional energy sources. A clever use of the active solar heating system could avoid consuming classical fuels during November, December and March. The ground heat exchanger is a reliable renewable source of energy. It provides heat during all the day and its (rather small) heat flux is increasing when the weather becomes colder. The air temperature at heater exit is normally lower than 46 °C. This is a good reason for the use of renewable energy to replace the classical fuel or the wood to be burn in the heater.

Analyzing mutual shading among buildings

A method for evaluating solar rights and shading requirements in an urban environment is presented. The method is embedded in a CAD tool developed and adapted for this purpose. With this tool one can analyze the mutual shading between buildings and other objects like trees. The purpose of this CAD tool is to allow the designer to plan efficiently the various functions of spaces among different structures, like buildings, as well as determining the location of the passive and active solar collectors. The method is a general one and allows a fast and efficient calculation of the ratio between insolated and total surface areas of any given examined object that is shaded by other irregular and nonplanar elements. The calculation of this ratio is carried out for all the months and hours for which either shading or insolation is required. The information obtained may serve as hourly input data for any dynamic simulation model which evaluates the thermal performance of the different external or internal shading systems. For a visual and a qualitative evaluation of the shadows among buildings, the suggested model permits a very realistic representation, in which the light source is defined according to the azimuth and the altitude of the Sun at the particular time of examination. The self shading and brightness of the different surfaces and the shadows cast by the various elements at the designated time are then generated and can be evaluated visually.

Performance Comparisons of Naturally- and Mechanically-Ventilated Solar-Assisted Swine Nurseries

ABSTRACT A modified-open-front (MOF), naturally-ventilated, solar-assisted (NVS) swine nursery and a mechanically-ventilated, solar-assisted (MVS) swine nursery were compared for building environment, energy efficiency, pig performance, and pig behavior during the winter of 1983. The two, 96-pig capacity nurseries utilized active solar collectors to provide in-floor heating in the sleeping area of each pen. Hovers were placed over the sleeping area of each pen. The MVS nursery utilized solar-preheated ventilation air. The NVS nursery had double-glazed solar windows to passively heat the interior space. The air temperature and relative humidity averaged 18C (59F) and 67% for all trials with more variation occurring in the naturally-ventilated building than in the mechanically-ventilated building. The NVS nursery used 72% as much energy as the MVS nursery and required 0.60 kWh less energy per pig than the MVS nursery. The two nurseries used only 1.4 to 2.2 kWh/pig as compared to 15.2 to 18.2 kWh/pig for a modeled mechanically-ventilated, conventionally-heated nursery for the same weather conditions. Significantly more pigs were observed utilizing the hovers in the NVS nursery than in the MVS nursery (P<0.05). The total floor area that was wetted due to dunging was also significantly greater in the NVS nursery than in the MVS nursery (P<0.05). Pig feed intake and feed to gain ratio were not significantly different (P<0.05) between the two buildings but the average daily gain for the NVS nursery was equal to or below that of the pigs in the MVS nursery.

Solar Applications in Industry and Commerce and Solar Energy Fundamentals and Designs—with Computer Applications and Active Solar Collectors and Their Applications

Solar Applications in Industry and Commerce and Solar Energy Fundamentals and Designs—with Computer Applications and Active Solar Collectors and Their Applications

A Method of Evaluating Solar Heat Storage in Livestock Buildings

ABSTRACT -AIR type solar collectors for use in livestock buildings preheat the continuous ventilating air. The excess collected heat is often stored in a thermal mass for later release to the building. The performance of a collector/ storage system is usually measured in terms of reductions in supplemental heat during the heating season. Monsen et al. (1981) proposed a design method to estimate the size of thermal storage for an active solar collector in human housing. He defined two extreme hypothetical cases: (a) zero thermal storage, ZTS, and (b) infinite thermal storage, ITS. The supplemental heat demand was estimated as a fraction of ZTS. Monsen et al. (1982) then extended the ZTS/ITS method of design and analysis to a passive solar Trombe wall. The objective of the present work was to develop the ZTS/ITS method of analysis for livestock buildings and test the method for a Trombe wall solar collector/storage system in a swine building.

Results from the Low-Energy Knivsta House

Knirsla House, near Uppsala. Sweden, is really a group of four flats within one single-storey building, linked by enclosed common areas and glazed-in ‘winter gardens’, the latter acting as passive solar collectors. Active solar collectors provide domestic hot water in summer, winter healing is by a low temperature system from the return circuit of the district heating network, and there is mechanical ventilation with heat recover: Detailed monitoring revealed performance mostly better than calculated, as discussed here by a member of the Royal Institute of Technology, Stockholm.

Energy conservation and solar houses

SYNOPSIS The delicate interplay between energy conservation with direct solar gain (passive energy) and active solar systems for space heating in solar houses is discussed. The following design parameters are analyzed, taking into consideration energy conservation and solar gain: a. the optimal slope of the collector roof b. southern windows or an active solar collector on south walls c. the trade-off between heavier insulation and a larger solar collector d. the optimal mass of the internal partitions The discussion is accompanied by results obtained from a case study.

Solar Air Heater in a Pre-Engineered Metal Building

ABSTRACT A pre-engineered metal building was modified to in-corporate an active solar collector air heater as an in-tegral part of the south wall. The solar collector system and the rock heat storage chamber performed well dur-ing tests. The modifications to the structure involved simple construction and readily available materials.