Economic analysis
The economic analysis of solar energy systems is carried out in order to determine the least cost of meeting the energy needs, considering both solar and non-solar alternatives. The method …
. Evacuated tube collectors
Conventional simple flat-plate solar collectors were developed for use in sunny and warm climates. Their benefits however are greatly reduced when conditions become unfavourable during cold, cloudy and windy days. …
Heat pump systems
Heat pumps use mechanical energy to transfer thermal energy from a source at a lower temperature to a sink at a higher temperature. Electrically driven heat pump heating systems have …
Concentrating collector acceptance angle
Another test required for the concentrating collectors is the determination of the collector acceptance angle, which characterises the effect of errors in the tracking mechanism angular orientation. This can be …
Parabolic dish systems
A parabolic dish concentrates solar energy onto a receiver at its focal point. The receiver absorbs the energy and converts it into thermal energy. This can be used directly as …
Ozone layer depletion
The ozone present in the stratosphere, at altitudes between 12 and 25 km, plays a natural equilibrium- maintaining role for the earth, through absorption of ultraviolet (UV) radiation (240-320 nm) …
Time value of money
It must be noted that a sum of money at hand today worth less than the same sum in the future, because the money at hand can be invested at …
Sun tracking concentrating collectors
Energy delivery temperatures can be increased by decreasing the area from which the heat losses occur. Temperatures far above those attainable by FPC can be reached if a large amount …
Solar refrigeration
Solar cooling can be considered for two related processes: to provide refrigeration for food and medicine preservation and to provide comfort cooling. Solar refrigeration systems usually operate at intermitted cycles …
Collector time constant
A last aspect of collector testing is the determination of the heat capacity of a collector in terms of a time constant. It is also necessary to determine the time …
Solar furnaces
Solar furnaces are made of high concentration and thus high temperature collectors of the parabolic dish and heliostat type. They are primarily used for material processing. Solar material processing involves …
Global climate change
The term greenhouse effect has generally been used for the role of the whole atmosphere (mainly water vapour and clouds) in keeping the surface of the earth warm. Recently however, …
Solar collector applications
Solar collectors have been used in a variety of applications. These are described in this section. In Table 10 the most important technologies in use are listed together with the …
Parabolic trough collectors
In order to deliver high temperatures with good efficiency a high performance solar collector is required. Systems with light structures and low cost technology for process heat applications up to …
Adsorption units
Porous solids, called adsorbents, can physically and reversibly adsorb large volumes of a vapour, called the adsorbate. Though this phenomenon, called solar adsorption, was recognised in the 19th century its …
Collector test results and preliminary collector selection
Collector testing is required in order to evaluate the performance of solar collectors and compare different collectors to select the most appropriate one for a specific application. As can be …
Solar chemistry applications
Solar energy is essentially unlimited and its utilization is ecologically benign. However, solar radiation reaching the earth is intermittent and not distributed evenly. There is thus a need to store …
Renewable energy technologies
Renewable energy technologies produce marketable energy by converting natural phenomena into useful forms of energy These technologies use the sun’s energy and its direct and indirect effects on the earth …
Thermosyphon systems (passive)
Thermosyphon systems, shown schematically in Fig. 24, heat potable water or heat transfer fluid and use natural convection to transport it from the collector to storage. The water in the …
Linear Fresnel reflector
LFR technology relies on an array of linear mirror strips which concentrate light on to a fixed receiver mounted on a linear tower. The LFR field can be imagined as …
Absorption units
Absorption is the process of attracting and holding moisture by substances called desiccants. Desiccants are sorbents, i. e. materials that have an ability to attract and hold other gases or …
Modelling of solar systems
The proper sizing of the components of a solar system is a complex problem which includes both predictable (collector and other components performance characteristics) and unpredictable (weather data) components. In …
Conclusions
Several of the most common types of solar collectors are presented in this paper. The various types of collectors described include flat-plate, compound parabolic, evacuated tube, parabolic trough, Fresnel lens, …
History of solar energy
The idea of using solar energy collectors to harness the sun’s power is recorded from the prehistoric times when at 212 BC the Greek scientist/physician Archimedes devised a method to …
Integrated collector storage systems (passive)
ICS systems use hot water storage as part of the collector, i. e. the surface of the storage tank is used also as an absorber. As in all other systems, …
Parabolic dish reflector (PDR)
A parabolic dish reflector, shown schematically in Fig. 11, is a point-focus collector that tracks the sun in two axes, concentrating solar energy onto a receiver located at the focal …
Industrial process heat
Beyond the low temperature applications there are several potential fields of application for solar thermal energy at a medium and medium-high temperature level (80-240 °C). The most important of them …
TRNSYS simulation program
TRNSYS is an acronym for a ‘transient simulation’ which is a quasi-steady simulation model. This program [111] was developed by the University of Wisconsin by the members of the Solar …
Solar collectors
Solar energy collectors are special kind of heat exchangers that transform solar radiation energy to internal energy of the transport medium. The major component of any solar system is the …
Direct circulation systems (active)
In direct circulation systems, shown schematically in Fig. 29, a pump is used to circulate potable water from storage to the collectors when there is enough available solar energy to …
Heliostat field collector
For extremely high inputs of radiant energy, a multiplicity of flat mirrors, or heliostats, using altazimuth mounts, can be used to reflect their incident direct solar radiation onto a common …
Solar industrial air and water systems
There are two types of applications employing solar air collectors the open circuit, and the recirculating applications. In open circuit, heated ambient air is used in industrial applications where because …
WATSUN simulation program
WATSUN simulates active solar systems and is developed by the Watsun Simulation Laboratory of the University of Waterloo in Canada [119]. It is a ready-made program that the user can …
Stationary collectors
Solar energy collectors are basically distinguished by their motion, i. e. stationary, single axis tracking and two- axes tracking, and the operating temperature. Initially, Table 1 Solar energy collectors Motion …
Indirect water heating systems (active)
Indirect water heating systems, shown schematically in Fig. 31, circulate a heat transfer fluid through the closed collector loop to a heat exchanger, where its heat is transferred to the …
