A comprehensive review of solar cooker with sensible and latent heat storage materials

Solar energy is available freely and does not create any pollution to the environment. Hence, researchers from all around the world are always working on solar energy applications with enhancement technologies. The solar cooker is one of the largest solar energy application, which is used to cook the food. However, because the solar energy is available only during the daytime, it is not widely used for industry as well as household application. To store the heat during the day, energy storage materials are used. Hence, this study presents a review of sensible and latent heat storage materials used to store the heat during daytime and use for other than daytime hours.     

Potential of renewable energy system utilisation at decentralised level in the state of Uttarakhand in India

ABSTRACT

Design and implementation of an effective dissemination programme for decentralised renewable energy system necessitate an accurate estimate of its utilisation potential. Hence, in this study, an attempt has been made to develop frameworks to estimate the utilisation potential of decentralised renewable energy systems in the state of Uttarakhand in India. Estimations imply large resource, technical and economic potentials of the domestic solar water heater, solar home system, solar lantern, family size biogas plant and improved biomass cookstove in Uttarakhand. With higher impact on the purchasing power of households, prevailing soft loan scheme has been found to be more appropriate than a capital subsidy for promoting the usage of decentralised renewable energy systems.     

Analysis and design of a robust controller for a grid-connected photovoltaic power plant

ABSTRACT

Application of renewable energy systems has a drastic impact on the present power system. In particular, solar photovoltaic power generation is expanding exponentially. Hence, in this article analysis and design of a 1 Mega Watt (1?MW) solar power plant has been modelled. The obtained power is given as an input to the voltage source converter, which contently regulates the active and reactive power by controlling the pulse width modulation signals. In this article, robust control schemes were discussed to support the required active and reactive power. Further, a detailed analysis has been presented at various fault conditions and the results are explored.     

Solar and heat pump system—Horsens swimming bath,Denmark

Over a number of years the local authorities of Horsens granted money to effect energy saving measures, the most cost-effective projects to be carried out first.

Recently a combined solar system and heat pump system has been constructed together with a centralized control and supervision system.

The solar system consists of 300 m² flat plate solar collectors without cover glass and insulation. The heat pump system consists of two water-to-water heat pumps with a total effect of 70 kW.

The total investment in the combined solar and heat pump system has been £93 000 (Dkr1.3m) including grants from the EEC and from the Danish Energy Administration.

The plant has now been in operation for more than 1 year and based on the measuring equipment installed it may be stated that the energy plant has given a saving of 2.8 TJ (670 Gcal) from district heating in the first year which allowing for a use of electricity of 187 MWh, amounts to a total of £14 000 (Dkr 195 000).

Based on a total investment of Dkr l.3m a yearly saving of Dkr 195 000 has been achieved, and speaking of an alternative energy plant this must be regarded as most satisfactory.     

Design and analysis of reflectivity for Mylar-coated solar dish

Energy is the key driver of the economy but energy crisis is a problem for the present-day source of energy. The concentrated solar power systems make use of different reflector configurations to convert the solar energy into high-temperature heat energy. Parabolic dish system is considered as the best suitable system for achieving high temperature and so it is opted for the study. Here, a solar dish is designed with an open diameter of 1.8?m (which is 2.5?m² in area), and reflective film is being used to reflect the solar irradiance and concentrated it in the focal point. A receiver of 1?mm thickness and 10?cm diameter is used at the receiver end to measure the temperature of the focal point. The setup has made to attain a maximum temperature of 940°C and average temperature of 850°C in the focal point at clear sky in a sunny day.     

Renewable energy for passive house heating: Model of the active solar heating system

The large windows on the south-oriented façade of a passive house strongly contribute to building space heating. These windows constitute the passive solar heating system. This paper studies the active heating system of a passive house, which includes the following sub-systems: (1) solar thermal collectors, (2) a water storage tank, (3) a secondary water circuit, (4) a domestic hot water preparation system and (5) an air ventilation and heating system. Models for all sub-systems are presented. The integrated model was implemented to Pirmasens Passive House (Rhineland Palatinate, Germany). The active solar heating system provides a smaller amount of heat than the heat provided by the passive solar heating system. Almost all the solar energy collected is not used for space heating but to domestic hot water (DHW) preparation. However, there is still a need for the classical water heater to operate all over the year. Almost all space heating thermal load is covered by using the classical air heater that operates mainly during the nights from November to April. The solar fraction lies between 0.180 in February and 0.679 in October, with a yearly average of 0.446. The study reveals that on a yearly basis it is more advantageous to use vertical south-oriented solar collectors instead of roof placed collectors.     

TRNSYS simulation for solar-assisted liquid desiccant evaporative cooling

ABSTRACT

Recently, desiccant cooling systems are well thought of as a competent method for controlling the water content in the air. A solar flat-plate collector has been used as it decreases the dependency on non-renewable resources. Solar-aided liquid desiccant systems have been used to reduce the dependency of air-conditioning systems on non-renewable sources of energy. Manipal’s humid and searing climate provides certain benefits in setting up such a system. The suggested system has reliability and equipment life and also takes complete advantage of the available solar energy for the renewal of the liquid desiccant. TRNSYS simulation is used to predict the efficiency and feasibility of the system. The temperature and energy-load variations were successfully obtained. An effective simulation was developed whereby the solar air conditioning of a room was indicated.     

Annual performance analysis of various energy storage materials in the upper basin of a double-basin solar still with vacuum tubes

ABSTRACT

A double-basin solar still with vacuum tubes showed impressive distillate output due to getting potable water from lower and upper basins. But it is also true that distillate output of the upper basin is lower compared with that of the lower basin. Hence, work is required to increase distillate output of the upper basin. In the present work, the upper basin was used with various energy-absorbing materials like black granite gravel, pebbles and calcium stones. The main purpose of using absorbing materials is to store excess energy during sunshine hours and release during off-sunshine hours. Therefore, the distillate output of the upper basin is increased compared with a still with only an upper basin. Hence, continuous work on a double-basin solar still with vacuum tubes (DBSWVT) by putting above energy absorbing materials is carried out during clear sky days of July 2014 and in June 2014. For comparison of a still with energy-absorbing materials, experimental readings of three days of May 2014 (1st, 5th and 9th) are chosen to determine the performance output of the present still with the said energy-absorbing materials. At last, yearly average distillate output of DBSWVT is carried out with said energy absorbing materials, cost of potable water/INR, energy payback time found 0.509 and 109 days. Also, on comparison with other researchers’ work in terms of percentage increment in distillate output 229.2% increment was found compared with a passive solar still.     

Renewable energy scenario in Telangana

ABSTRACT

This article presents an analysis of the current situation of renewable energy in Telangana, India, and predicts the future of renewable energy resources in the state. In India, maximum power is generated using conventional energy sources such as coal and mineral oil. They highly pollute the atmosphere. If new power plants are to be set up, then the import of highly volatile fossil fuels is inevitable. Though nuclear energy is a good alternative to reduce fossil fuel consumption, it is equally hazardous to human life. Hence, the energy world should think of judicious use of renewable energy resources such as solar, wind, ocean, biomass, and geothermal energy. The R&D activities carried out in India in the past three decades have shown good progress in finding a feasible solution to the problem of searching new renewable energy resources. Telangana is the state committed to use the renewable resources in a better way to fulfil its electrical energy needs. This article also analyses the current energy needs of the state and forecasts energy consumption and production in the future with the aim of finding whether the state can continue on the path of development and augment its renewable energy resources.     

A dual-mode internal window management device for energy conservation

The design of a simple energy conserving window management system is described, and its heat transfer characteristics are calculated. The device serves as a quasi-active solar collector during winter daytime, provides added insulation comparable with that of vented storm windows during winter nighttime, and rejects solar heat during summer cooling periods. The problem of avoiding the intensity of direct sun through windows while obtaining essentially all the associated heat is effectively solved with a window system of this type. The results of the numerical modeling show that the dual shade:will be approximately 90% as energy efficient as an unshaded window while intercepting direct sunlight;will save about 40% on energy losses through a single pane window during winter nighttime;will reduce solar heat gain by about 70% during peak-power summer air conditioning periods.     

Numerical analysis on heat transfer characteristics of ionic liquids in a tubular heat exchanger

ABSTRACT

The efficiency of the solar thermal system depends on the performance of the solar collectors. There is a need to operate solar collector at higher possible temperature to attain maximum efficiency limits. However, the performance of the collector system is limited by the heat transfer characteristics of the working fluid called as the heat transfer fluid (HTF). Water is widely used as the HTF in the solar collector, but the major problem of using water as the HTF is its limited operating temperature. The objective of the work is to investigate the heat transfer characteristics of ionic liquids in tubular heat exchanger (HE) suitable for the solar thermal application. The HE was designed for a heat duty of 1?kW based on the thermal transport property of available ionic liquids and the computational fluid dynamics (CFD) analysis was performed. The results indicate that there is only minimal deviation between the assumed and CFD data.     

Experimental analysis of single-basin solar still with porous fins

ABSTRACT

The present research paper explains the experimental analysis of the single-basin solar still with attachment of porous fins on the absorber plate. Here, experiments have been conducted on the single-basin sola still with and without attachment of porous fins. Generally, fins are used in the solar still to reduce the preheating time of water and attain positive water and inner glass cover temperature during morning hours for increment in distillate output. Series of experiments were performed in the Government Engineering College Patan during May 2017 during sunshine hours. Various temperatures such as that of water, inner glass cover and solar insolations have been measured by standard instruments. From the experiment, it was found that the distillate output after attachment of fins was 3.8?L and that of the conventional solar still was 2.67?L. Hence, a percentage increment of 42.3% was found by use of porous fins in a solar still.     

太阳能热泵-低谷电与地板辐射采暖系统联合运营方式探讨

论述了太阳能热泵与低谷电作为地板辐射采暖热源的可行性和必要性,提出了一种利用太阳能和低谷电作为地板辐射热源采暖的方案,讨论了系统在冬季采暖期的运行方式.太阳能是一种无污染、无穷尽的自然能源,但具有不稳定和不可靠性,特别在冬季尤为明显.而低谷电作为太阳能的辅助能源,却可以有效弥补太阳能的不足.这两者结合具有节能、环保等优点.终端利用地板辐射采暖与太阳能热泵-低谷电系统提供热水温度特点一致,能够提高热泵制热性能系数,并且具有良好的舒适性和节能效果.因此,在我国北方地区,太阳能热泵与低谷电联合供暖在建筑领域值得推广和应用.     

Prediction of solar heat gain of double skin facade windows

A linear model involving the solar heat gain coefficient and U value is often used to calculate the solar heat gain of traditional windows; however, it is not known if such linear model is applicable to double skin facades, which is typically featured by ventilated cavity and often with blinds inside. This paper reports on an experimental investigation into the relation between the two coefficients and the energy gain by a double skin facade without blinds. A small-scale solar calorimeter was constructed to measure the energy gain of a double skin facade window about 1.1 m high. Four tests with solar radiation intensity ranging from 205 to 793 W/m² showed that the energy gain can be represented by such linear model. The solar heat gain coefficient can be determined from the data fitting process with more accuracy than the U value, which, being a minor determinant of the heat flow in the presence of the solar radiation, may require more data for reasonable accuracy. The advantage of this linear model lies in its simplicity, which makes it easy to incorporate into present building energy simulation tools.     

Fuzzy logic energy management for a microgrid with storage battery

ABSTRACT

This article presents the development of an energy management system using fuzzy logic applied to a microgrid that combines photovoltaic solar energy, wind energy and a storage system with batteries. The model was developed using LabVIEW software and allows to obtain performance results of the photovoltaic generator, the wind turbine and the battery bank. The energy management system can be controlled in real time to take advantage of existing weather conditions. The results indicate that the fuzzy logic system guarantees the continuous operation of the load through the energy resources of the microgrid. The designed microgrid allows to generate 63,288?kWh/year of photovoltaic solar energy and 40,175?kWh/year of wind energy.     

A comprehensive review of the solar dryer

ABSTRACT

Drying of agricultural products is an energy-demanding process. High costs, scarcities in fossil fuels and environmental threats attract the use of solar energy as an alternate source, especially in developing countries. Increasing environmental concerns led to the use of clean and green energy resources in the field of drying agricultural products. A solar dryer integrated with a thermal energy storage system is reasonably efficient for continuous and uniform drying of agricultural produce in the temperature range of 40–75°C which is the requisite for drying most of the products. Such dryers have become a natural choice to replace drying systems based on fossil fuels. Many studies have been performed till date by a number of researchers for the last few decades for drying agriculture and food products by a solar dryer. This review paper primarily presents an appraisal of the significant contributions made so far in the field of solar drying systems, with the latest updates in drying technology. Solar dryers which offer drying during off-sunshine hours have been specially mentioned. Some novel ideas like use of phase change materials and desiccant materials which enhance the performance and effectiveness of the dryer have also been attempted.     

Performance analysis on improved efficiency in a hybrid solar still and solar heater

ABSTRACT

This paper deals with solar still. Today fresh water demand is increasing continuously, because of the industrial development, intensified agriculture, improvement of standard of life and increase in the world population. Only about 3% of the world water is potable and this is not evenly distributed on the earth. On deserts and islands, underground water is not readily available and the cost of shipping to other places is high, it is worthwhile to consider producing potable water from saline water using solar energy that is in abundant in deserts. The efficiency of the solar still can be increased by increasing the evaporation rate and by minimising the convective and radioactive losses in still. The evaporation rate can be increased effectively by coating the still base with photocatalyst materials or by pre-heating the inlet water of still. The easily available GAC is one of the best photocatalyst materials suitable for the solar still for enhancing the evaporation rate. Solar-still technology is a renewable and efficient technology for pre-heating the inlet water to solar still. Hence the combination of GAC coating and solar-still technology can increase the evaporation rate and efficiency of solar still.     

Build-up and performance test of a novel solar thermal roof for heat pump operation

Global increase in energy demand and fossil fuel prices loaded ever-increasing pressure on identifying and implementing new means to utilise clean and efficient energy resources. Due to the environmental benefits, technical and economic possibilities of Solar-Assisted Heat Pump Systems, there has been a growing interest for such hybrid systems with a variety of system configurations for various climates. International Energy Agency Task 44 of the Solar Heating and Cooling Programme has recently started working on finding methods to most effectively use solar heat pump systems for residential use. In the present study, a novel solar thermal roof collector was developed by primarily exploiting components and techniques widely available on the market and coupled with a commercial heat pump unit. The proposed indirect series Solar-assisted Heat Pump system was experimentally tested and system performance was investigated. Yet, the analysis based on indoor and outdoor testing predominantly focuses on the solar thermal roof collector. A detailed thermal model was developed to describe the system operation. Also, a computer model was set up by using Engineering Equation Solver to carry out the numerical computations of the governing equations. Analyses show that the difference in water temperature could reach up to 18°C while maximum thermal efficiency found to be 26%. Data processing of the series covering the test period represents that Coefficient Performance of the heat pump (COP_HP) and overall system (COP_SYS) averages were attained as COP_HP?=?3.01 and COP_SYS?=?2.29, respectively. An economic analysis points a minimum payback period of about three years for the system.     

关于太阳能辅助水源热泵系统联合冬季供暖的研究

随着我国能源的紧缺和环保意识的加强,太阳能、浅层地热能作为可再生能源,越来越受到人们的重视。但无论是太阳能系统,还是水源热泵系统,单独运行时均有一定的局限性,两者联合运行的应用很少。通过实际工程分析,太阳能系统与水源热泵系统可以联合工作,并可达到预期的室内空调温度;对太阳能系统与水源热泵系统联合运行的运行费用做了技术分析,证实这种联合模式节能效果十分明显。