Mogućnosti korišćenja akumulatora toplote sa promenom faze u postrojenjima na biomasu

Abstract

Korišćenje akumulatora toplote na postrojenjima koja koriste obnovljive izvore energije (biomasu) predstavlja dobar način da se poveća njihova energetska efikasnost. Glavni razlog ugradnje akumulatora toplote je taj što je opterećenje kotlova na biomasu retko kada konstantno, jer se menja tokom dana i tokom godine, zavisno od uslova korišćenja kotla. U radu su prikazani rezultati razvoja akumulatora toplote kod kojih se materijal za akumulaciju topi na atmosferskom pritisku, omogućavajući na taj način korišćenje energije faznog prelaza za skladištenje energije dobijene sagorevanjem biomase. Akumulatori toplote ovog tipa omogućavaju veću količinu akumulirane toplote po jedinici zapremine, a takođe, u zavisnosti od radnog medijuma, omogućavaju dostizanje viših temperatura radnog medijuma, što je neophodan uslov kod postrojenja sa kogeneracijom. U svrhu eksperimentalnog ispitivanja strujnih i termičkih procesa u akumulatoru toplote konstruisan je i izrađen prototip takvog akumulatora toplote. On je cilindričnog oblika, zapremine 77 dm3. Radni material se greje električnim grejačem snage 2,4 kW, a hladi se vazduhom. Kao radni medijum korišćen je parafin. Merenja su vršena kako u nestacionarnom tako i u stacionarnom režimu rada. Dobijena je obimna baza eksperimentalnih podataka, koji će se koristiti u numeričkom istraživanju, za razvoj modela i verifikovanje njegovih rezultata.

The use of thermal storage tanks (TST) infacilitiesthat use renewable energy resources (biomass) represents a good way to increase their energy efficiency.The main reason for their introduction is the fact that the energy production in biomass boilers is seldom constant, and frequently changes during theday, depending on the conditions of its use. This paper presents the results in the development of TST in which the thermal storage material is melted on atmospheric pressure,enabling on that way the use of the energy of phase change for energy storage. TST of this type enable more thermal energy storage per volume unit, but also (depending of the working medium) enable higher temperatures of the working medium, which is necessary in the co-generated facilities.For the purpose of the experimental research of thermal and flow processes in TST a prototype of TST was designed and made. It has a cylindrical shape, with the working volume of 77 dm3. Theworking material is heated by 2.4 kW electric heater positioned along the TST axes, and is cooled by the air. For the purpose of this workparaffin as a working medium was used.Measurements were performed for non-stationary as well as for stationary working regimes. As a result, an extensive set of experimental data was obtained, which will serve in the numerical study, as a basis for the developing a numerical model to verify its results.