Detailed design of heat exchangers in matlab for organic rankine cycle applications

Abstract

Consulta en la Biblioteca ETSI Industriales (Riunet)

[EN] The use of Organic Rankine Cycles (ORC) is increasing due to the high thermal efficiency that can be reached compared to a water-driven Rankine Cycle (RC) for low temperature heat sources. Besides, a good organic working fluid must have good safety characteristics as non-toxic and non-flammable, low environmental impacts, low cost, good availability, etc. There exits different types of organic fluids like hydrocarbons, hydrochlorofluorocarbons, hydrofluorocarbons and chlorofluorcarbons. In this present study, MATLAB models for heat exchangers with ORCs were developed. An existing MATLAB code for basic engineering applications was extended with correlations for pressure drop calculations, heat exchanger geometry etc. The final design was verified by ASPEN PLUS simulations. Several simulations were carried out in MATLAB and compared to real data from a geothermal power plant. In these simulations, different correlations for pressure drops and heat transfer coefficients were used. Two types of heat exchangers have been designed: a preheater or economizer and an evaporator. After MATLAB simulations have been taken placed, ASPEN simulations were verified. Finally, different working fluids were simulated MATLAB models. These MATLAB models were chosen from a comparison between MATLAB and ASPEN models. The existing MATLAB code has been optimized including new correlations. Results obtained from MATLAB models are good approximations to real data. The errors between MATLAB simulations and real data are between reasonable ranges. Finally, simulations with other working fluids were carried out in order to verify the applicability of the derived model for different systems.