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[en] Graphical abstract: - Highlights: • We simulate a thermosiphon collector associated to a single zone using TRNSYS. • We examine the temperature of water in collector, in tank and in single zone. • We study the temporal evolution of the temperature and the energy for 11 h operation in January and 2880 h operation in winter. • The system gives good results in all operating states. • The use of solar energy in the residential building is interesting. - Abstract: The novelty of this paper is the coupling between a thermosiphon collector and a single zone with the following details; a thermosiphon system (TYPE 45) which uses the solar energy as an unlimited renewable energy to produce the heat by using an internal coupling of a flat plate collector and a storage tank in a closed loop realized in TRNSYS. Consequently, the user simply utilizes TYPE 45 as thermosiphon ready to be run, and a single zone (TYPE 19) is a complex type which is designed for residential buildings that can be specified by the user in order to obtain an acceptable heating within a house. The user specified the characteristics of the internal space, external weather conditions, walls, windows, and doors. To facilitate this description, the parameters and inputs for this component are organized in separate table according to a logical structure. According to us, the choice of this model of thermosiphon coupled with a single zone can have multiple interesting engineering applications, in particular ameliorating the mode of the heating in residential buildings. Two flat plate collectors of aperture area of 6 and 8 m2 are modeled. The solar fraction of the entire system is used as the optimization parameter. The temperature of the water in the storage tank, the collector’s temperature, the temperature inside and outside the house, the solar fraction for different collector areas and the total energy were also measured in 11 h operation in January and 2880 h operation in winter. The average solar fraction obtained was 85% and the system could cover all the hot water needs of a house of six people. The maximum auxiliary energy was needed during 11 h operation in January and 4 months in winter. The results show that by utilizing solar energy, the designed system could provide 40–70% of the hot water demands in winter
[en] It is shown that in solar constant measurements if the scattered solar radiation in to be taken into account the function of intermediate transformation of three wavelengths photometer may have a dual form of writing. The possibility of measuring of solar constant with three wavelength photometer taking into consideration the aerosol scattering of light is shown
[en] Highlights: • A forced-circulation solar water heater system for domestic use was investigated. • Six different climatic zones of Morocco were simulated. • Flat plate and evacuated tube installations were compared. • Solar fractions for the different scenarios were given. - Abstract: The aim of this study is to assess the technical feasibility of solar water heaters (SWH) under Moroccan conditions. Annual simulations in six different regions for two technologies: flat plate and evacuated tube collectors were carried out using TRANSOL program. It is found that high values of solar fraction can be reached in almost the studied regions with the preference of using evacuated tube collectors. Furthermore, the study emphasizes that the location and the climate are determinant parameters on the overall performance of solar water heating systems
[en] Full text: Concentrating solar power (CSP) technologies could be one of the major contributor to worlds future energy needs and which would be cheap and clean sources of energy. This would improve energy utilization, higher conversion efficiency with reliable and affordable supply of electricity to the public. The proposed approach is using different size and depth of solar dish concentrators to improve solar fraction using the aluminium foil as reflector. In this paper, different measurement of solar concentrators is investigated and aims to aims to introducing an improved methodology for solar fraction on incoming solar energy in wet climate. (author)
[en] Solar energy is the most promising source of clean, renewable energy and it has the greatest potential of any power source to solve the world's energy problems. However, the problem, is how best to harness this vast amount of solar energy. Nevertheless, even if highly efficient Concentrating Solar Power (CSP) could be made cheaply, there would be considerable change in solar power. This technology is expected to be more efficient and to achieve a manufacturing cost of less than $1/W near future. This paper reviews and elaborates the methodology utilized to design and fabricate the solar dish concentrator and outlines the parameters that can be used to increase the efficiency of solar fraction in parabolic dish concentrator under wet climate environment in Malaysia. The study finally provides ideas to the continually increasing ability of these technologies to concentrate and harness solar energy for electricity production and thus eliminate the growing concern over climate change and how it will hurt the region's environment, human health and economy. (author)
[en] The thermodynamic model we develop in this paper considers (i) the external irreversibilities of the endoreversible models; (ii) the irreversibilities due to heat losses; and (iii) the generation of internal entropy due to pressure drops and the temperature and concentration gradients. We considered: (i) external heat losses between the generators of high and intermediate pressures and the ambient and between the ambient and the evaporator; and (ii) internal heat losses from the generators towards the condensers and from the absorber towards the evaporator. This simple but precise model faithfully represents the trend towards efficiency variation at partial loads. We have used the model to analyse the behaviour of a water-LiBr double-stage absorption chiller with 200 kW of cooling power. This machine can operate in summer as a double-stage chiller driven by heat at 170 oC from natural gas, as a single-stage chiller driven by heat at 90 oC from solar energy, or simultaneously in combined mode at both temperatures. It can also operate in winter in 'double-lift' mode for heating with a driving heat at 170 oC from natural gas. We studied the efficiency of the machine at partial loads for several solar fractions and the distribution of the heat transfer areas between the various components of the chiller
[en] Highlights: ► Potential of utilizing a solar cooling system in Jordan is investigated. ► The suggested system will be used for cooling a 41 m2 laboratory. ► Solar collectors of 196 m2 are required for an 8 kW solar air-conditioning system. ► The estimated payback period of the solar cooling system exceeds the project life time of the project. - Abstract: In this paper, the potential of utilizing a solar cooling system to improve the indoor air quality is investigated. The analysis is performed for a 41 m2 with a 3.65 m height laboratory located at Mango Center for Scientific Research – University of Jordan in Amman. The hourly ambient temperatures and the monthly solar radiation in Amman are recorded. The calculations of the cooling demand were done using two methods, i.e. manual calculations and block load software. For the analysis, the internal loads of lightning, computer, etc. and the building envelope (e.g. double glass, no shading) were considered. The results show that proposed solar collectors of 40 m2 area can provide solar heat for an 8 kW solar air-conditioning system. Moreover, domestic hot water (solar fraction up to 100%) and solar heating (approx. 15–25% solar fraction) could be also provided, with the solar air-conditioning system, for the centre. An economic study was also carried, which showed that the estimated payback period of the solar cooling system, exceeds that of project life time of the project, which is assumed to be 24 years unless the government of Jordan issues a new law for renewable energy that grants incentives, exemptions and subsidizes projects that invest in solar energy applications by about 40% of initial investment cost of the system.
[en] A solar plant for hot-water production was investigated by the dynamic simulation code TRNSYS coupled with PREVIS code. Typical daily university campus consumption for a 240 students was considered. The hot-water demand temperature (45 degree centigrade) is controlled by a conventional fuel auxiliary heater and a tempering valve. The fluids circulate by pumps activated by electricity. Annual energy performance, in terms of solar fraction, was calculated for Tangier.(Author)
[en] Highlights: • A mathematical model for glazed transpired collectors (GTC) is developed. • Glazing results in optical loss, but it decreases convective heat loss effectively. • Thermal performance of GTC shows considerable improvement on flat-plate collectors. • GTC using recirculated air is applicable to space heating in cold climates. - Abstract: Although unglazed transpired collectors (UTC) succeed in industrial ventilation applications, solar fraction is very low when they are used in space heating in cold climates due to the lower exit air temperature. Considering the potential for glazed transpired collectors (GTC) using recirculated air for space heating applications in cold climates, a mathematical model is developed for predicting the thermal performance of GTC. Simulation results show that although glazing results in optical loss, it could decrease convective heat loss resulted from high crosswind velocities effectively. For a solar radiation of 400 W/m2, an ambient temperature of −10 °C, and a suction velocity of 0.01 m/s, the exit air temperature of GTC is higher than that of UTC for crosswind velocities exceeding 3.0 m/s. By comparison with a conventional flat-plate solar air collector operating under the same conditions, the thermal performance of GTC shows a significant improvement. For a five-storey hotel building located in the severe cold climate zone of China, case study shows that the annual solar fraction of the GTC-based solar air heating system is about 20%, which is two times higher than that of the flat-plate collector-based system and nearly nine times higher than that of the UTC-based system respectively. Hence, an enormous amount of energy will be saved with the application of GTC to space heating in cold climates
[en] In this paper, the feasibility of a medium temperature, low profile concentrated solar thermal collector integrated with latent heat thermal energy storage (LHTES) is investigated. The proposed modular integrated collector storage (ICS) system consists of six solar receiver units and seven cylindrical shell and tube LHTES tanks. By implementing an innovative optical concentration assembly and an internal linear tracking mechanism, the collector can concentrate beam radiation to the tube receivers during the highest flux hours of a day without any external or rotational motion. The collector's efficiency correlations were obtained experimentally and its integrated performance – with the LHTES units – was evaluated numerically. To demonstrate the potential of this proposed ICS system, an annual analysis was carried out for a characteristic industrial application – a dairy dehydration process that requires a constant 50 kW_t_h of heat in the 120–150 °C temperature range. It was found that adding the storage units will increase the capital costs by ∼10%, but it can increase the annual thermal output of the system by up to ∼20%. A solar fraction of 65% was achievable with some design alternatives, but the optimum techno-economic design had a solar fraction of ∼35% and an annual charging efficiency of nearly 100%. It was also found that if the capital cost of the ICS (collector and LHTES tank) system could be reduced by 50% from an estimated ∼1000 US$/m"2 to ∼500 US$/m"2 through mass production and/or further design optimizations, this system could provide industrial process heat with a levelized cost of heating (LCOH) of ∼0.065 US$/kWh_t_h. - Highlights: • An innovative ICS system was proposed and analyzed for industrial heat applications. • The optimum design can achieve a ∼35% solar fraction with ∼100% charging efficiency. • A 0.12 US$/kWh LCOH was found, but further reductions could result in 0.065 US$/kWh. • Costs reductions of the ICS to 250–400 US$/m"2 could yield a 10 year payback time.