Molla Engineering

 There are basically two types of solar collector: non concentrating stationary and concentrating. A non concentrating collector has the same area for intercepting and for absorbing solar radiation where as a sun tracking concentrating solar collector usually has concave reflecting surfaces to intercept and focuses the sun's beam radiation to a smaller receiving area thereby increasing the radiation flux.     Stationary Collectors: These collectors are permanently fixed in position and do not track the sun. Three types of collectors fall in this category: 1.  Flat plate collectors (FPC) 2.  Stationary compound parabolic collectors (CPC) 3.  Evacuated tube collectors (ETC) 1. Flat-plate Collectors (FPC): A typical flat-plate solar collector is shown in Fig. (1). When solar radiation passes through a transparent cover and impinges ·on the blackened absorber surface of high absorptivity, a large portion of this energy is absorbed by the plate and then tra...

  A parabolic trough is a type of solar thermal collector that is straight in one dimension and curved as a parabola in the other two lined with a polished metal mirror. The energy of sunlight which enters the mirror parallel to its plane of symmetry is focused along the focal line, where objects are positioned that are intended to be heated. For example food may be placed at the focal line of a through which causes the food to be cooked when the trough is aimed so the sun is in its plane of symmetry. Further information on the use of parabolic troughs for cooking can be found in the article about solar cookers. For other purpose there is often a tube frequently a Dewar tube which runs the length of the trough at its focal line. The mirror is oriented so that sunlight which it reflects is concentrated on the tube which contains a fluid which is heated to a high temperature by the energy of the sunlight. The hot fluid can be used for many purpose. Often it is piped to a heat engine ...

  Greenhouse is an enclosure where proper environment is provided for growth and production of crops, vegetable and flower plants under adverse climatic conditions. By controlling the environment a particular vegetable or flower can be grown throughout the year. The design of a greenhouse depends on local climatic conditions. In cold countries, winter greenhouse provide supplementary heat to maintain adequate temperature during cold months when solar insolation is low. In tropical countries, the solar insolation and ambinet temperatures are quite high and therefore summer greenhouse are used to maintain low temperatures inside and allow just sufficient sunlight for photosynthesis. Greenhouse for arid zone are designed to conserve water resources. Although there is slight variation in the environmental needs of each variety of plants for best production, basically they all require moderate temperatures and light, adequate quantities of carbon dioxide, oxygen, mineral nutrients, air ...