Thermo-economic evaluation of ORCs for various working fluids

Abstract

a b s t r a c tAn inclusive component-level technical and economic assessment procedure for the general design and operating strategy of Organic Rankine Cycles (ORC) for use across major application categories (waste heat recovery, solar thermal, geothermal) and sub-MW scales can be an important tool for leveraging the cost-effective deployment of low and medium temperature power cycles. Previous analyses and design approaches tended to focus on thermodynamic efficiency rather than financial performance. To bridge this gap, a general thermo-economic optimization of sub 500 kWe ORCs is developed using a 7-dimensional design space with minimum investment cost per unit of nameplate electricity production as an objective function. Parameters used include working fluid, heat source temperature, pinch in condenser, boiler (HEX) and regenerator, expander inlet pressure and air cooled condenser area. Optimized power block configurations are presented for the application of ORCs with waste or ''free" heat sources and solar heat input for power scales of 5, 50 and 500 kWe to facilitate rapid selection of design parameters across a wide range of thermal regimes. While R152a yields the lowest cost ORCs in the case of the former, isopentane is found to be more cost effective in the latter case for heat source temperatures between 125 and 275°C.

Prediction of the ORC Working Fluid’s Temperature-Entropy Saturation Boundary Using Redlich-Kwong Equation of State

“…Ever since this technology was introduced, the choice of a suitable working fluid plays a key role in the application. Optimization algorithms not only involve design parameters as in conventional Rankine Cycles [ 3 ], but working fluids as well [ 4 , 5 ]. Working fluid selection criteria generally include thermodynamic and physical properties, chemical stability in the desired temperature range, compatibility, environmental impacts, safety, and production costs, which also refers to the availability of the fluid.…”

Design and off-design optimization procedure for low-temperature geothermal organic Rankine cycles

“…Isobutane (R600a) [46] is chosen as the working fluid because of its low environmental impact [47], high power output and the low cost of hydrocarbons [21,48]. The thermodynamic and environmental properties of Isobutane are summarized in Table 4.…”

Expander Technologies for Automotive Engine Organic Rankine Cycle Applications

“…Expansion machines are typically the most costly component [192][193][194][195][196] as they need to be precision engineered [197]. It is worth mentioning that open literature lacks a direct cost comparison between the various types of expanders.…”