Tag Archives: Solar collector

267-274 A. Aboltins and J. Palabinskis
New types of air heating solar collectors and their use in drying agricultural products
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New types of air heating solar collectors and their use in drying agricultural products

A. Aboltins* and J. Palabinskis

Institute of Agricultural Machinery, Latvia University of Agriculture, Cakstesblvd. ⁵, Jelgava, LV – ³00¹, Latvia;
*Correspondence: aivars.aboltins@inbox.lv

Abstract:

The  aim  of  this  research  was  to  make  new  types  of  air  heating  solar  collection  foragricultural production drying and check their operation. In ²0¹¹ and ²0¹² were obtained twoLatvian Republic Patents for air heating solar collectors. One for an autonomous, compact air-heating solar collector, the other one for a cylindrical crop production drying device with solarcollector  that  can  be  used  for  drying  products.  So  there  are  two  different  types  of  dryingfacilities with solar collectors using sun-warmed air: cylindrical crop production drying device,and  autonomous,  compact  crop  production  drying  facility.  Cylindrical  facility  is  tested  fordrying  ¹⁹.⁵%  wet  wheat.  Autonomous,  compact  crop  production  drying  facility  is  tested  forfresh  carrots  and  apples  ⁵–¹0 mm  slices  drying,  using  ambient  air,  heated  with  the  solarcollector.  For  experimental  results  on  carrot  and  apple  slices  the  layers  of  humidity  andtemperature  changes  in  the  drying  process  are  given.  Grain  temperature  distribution  in  wetwheat layers during drying with heated ambient air depending from sun radiation is given.

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5-11 A. Aboltins, J. Palabinskis and G. Ruškis
The Investigations of Heating Process in Solar Air Heating Collector
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The Investigations of Heating Process in Solar Air Heating Collector

A. Aboltins¹, J. Palabinskis¹ and G. Ruškis²

¹Institute of Agricultural Machinery, Latvia University of Agriculture,
Cakstes 5, LV3001, Jelgava, Latvia; e-mail: aivars.Aboltins@inbox.lv
²Institute of Agricultural Machinery, Latvia University of Agriculture,
Cakstes 5, LV3001, Jelgava, Latvia; e-mail: Janis.Palabinskis@llu.lv

Abstract:

The aim of the research is to find the optimal technical solutions, utilized materials as absorbers, operation parameters and power possibilities for a solar collector. Different absorbers of sun radiation, the absorbers’ ability and efficiency in air heating solar collector are compared. 0.1 x 0.5 x 1.0 meters long equipment for experimental research into the materials of solar air heating collector was built. The experimental data were measured and recorded in the electronic equipment REG. The investigations are devoted to the sun following collectors, which guarantee perpendicular location for all experimental time of the plane of absorber to the flow of the sun radiation. The collector covered material was a polystyrol plate and absorbers were: a) black colored steel tinplate and b) slices of black colored beer cans. The use experimental data received expressions of heating degree of air in collector depending on sun radiation and distance from absorber (steel tinplate) at 35 cm and 60 cm from inlet. In favorable weather conditions the heating degree of the ambient air with absorber black colored slices of beer cans reaches more than T = 10o C at the air velocity 0.9 m s-1.

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263-269 I. Pelēce, U. Iljins, and I. Ziemelis
Theoretical calculation of energy received by semi-spherical solar collector
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Theoretical calculation of energy received by semi-spherical solar collector

I. Pelēce, U. Iljins, and I. Ziemelis

Latvia University of Agriculture, Liela str. 2, Jelgava LV3000; e-mail: ilze.pelece@llu.lv

Abstract:

Solar energy is widely used as an environmentally friendly energy source in many countries, Latvia among them. However, geographical and climatic conditions in Latvia, low maximal height of the sun and maximal irradiance, as well as comparatively great cloudiness, present particular challenges. Long days and the long path of the sun in summertime means traditional constructions of solar collectors are not efficient enough for use in Latvia.A new principle in the construction of the solar collector has been developed: a solarcollector with the absorber in the shape of a semi-sphere. It has advantages in comparison with the traditional fixed flat-plate model: it effectively receives both direct and diffuse solar radiation all day. In addition, it is durable against the destructive impact of the wind.This article reports theoretical calculations of received energy which have been carriedout, based on continual visible position of the sun in the sky. Results of these calculations have shown that on a clear sunny day, a semi-spherical collector with the base of 1 m2 receives 1.3 times more energy than a flat-plate collector positioned at optimal (approx. 40o) inclination, and 1.6 times more than the flat horizontal one. In cloudy conditions, the difference is greater because of greater diffused radiation.Such a semi-spherical solar collector has been constructed. Experimental investigation ofthe received heat energy from the semi-spherical solar collector will be carried out in field conditions this summer.

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