COMPARATIVE ANALYSIS OF WORKING FLUIDS IN SOLAR JOULE BRAYTON COGENERATION ENGINES

Autor/autori: Gheorghe DUMITRASCU, Michel FEIDT (Franta), Bogdan HORBANIUC

Rezumat: Lucrarea include o analiza comparativa a influentei naturii agentului de lucru asupra performantelor unui ciclu solar cogenerativ Joule Brayton de mica putere. Schema constructiva a motorului Joule Brayton a presupus sistemul: compresor centrifug – turbina centripeta – captator/concentrator de radiatie solara– recuperator intern de caldura, ce poate fi utilizat pentru puteri mici. S-au considerat trei posibili agenti de lucru, aer, azot si dioxid de carbon. Pentru a obtine rezultate numerice cat mai veridice, schema numerica de calcul a considerat calduri specifice variabile, rapoarte de comprimare si randamente izentropice corespunzatoare tipurilor de compresor si turbina adoptate, diferite grade de concentrare a radiatiei solare prin intermediul temperaturii maxime pe ciclu. Analiza numerica a evidentiat ca alegerea unui agent de lucru trebuie facuta pentru fiecare aplicatie in parte, in functie si de conditii restrictive specifice diferite de cele termodinamice, cum ar fi de exemplu raportul dintre fluxul termic cerut de consumatorii de caldura si puterea furnizata impusa de consumatorii acestei utilitati energetice, tehnologii de fabricatie si valoarea investitiilor specifice, etc.

Cuvinte cheie: ciclu solar cogenerativ Joule Brayton, agenti de lucru, performante termodinamice, schema logica de calcul

Abstract: The paper includes a comparative analysis of the effect of the working fluid type upon the performances of a small solar cogeneration Joule Brayton cycle. The engine scheme considered the setup: radial compressor – centripetal turbine – concentrating solar power (CSP) heat exchanger – internal recovering heat exchanger – and external cogeneration heat exchanger. They were evaluated three working fluids, air, nitrogen, and carbon dioxide. The numerical code involved variable heat capacities, compression ratios and isentropic efficiencies typical for the chosen compressors and gas turbine, and various solar radiation concentrating degrees by the intermediary of the maximum temperature on the cycle. The numerical analysis emphasized that the choosing of a certain working fluid must follow also extra non-thermodynamically based real operational restrictive conditions, such as for instance the operational heat per power ratio, technological approaches and specific financial investments etc.

Keywords: solar cogeneration Joule Brayton cycle, working fluids, thermodynamic performances, numerical algorhytm.

DOWNLOAD PDF