The Application of Rotary Vane Expanders in Organic Rankine Cycle Systems—Thermodynamic Description and Experimental Results

Abstract

Small (10-100 kW) and micro (0.5-10 kW) Organic Rankine Cycle (ORC) power systems are nowadays considered for local and domestic power generation. Especially interesting are micropower applications for heat recovery from dispersed low potential (85-150°C) waste and renewable heat sources. Designing and implementing an ORC system dedicated to energy recovery from such a source is difficult. A proper working fluid must be selected together with a suitable expander. Volumetric machines can be adopted as a turbine altertiative in small-capacity applications under development, like, e.g., domestic cogeneration. Scroll and screw expatiders are a common choice. However, scroll and screw expanders are complicated and expensive. Vane expanders are mechanically simple, commercially available and cheap. This paper documents a study providing the preliminary analysis of the possibility of employing vane-expanders in mini-ORC systems. The main objective of this research was therefore a comprehensive analysis of the use of a vane expander for continuous operation with a low-boiling working fluid. A test-stand was designed and set up starting from system models based on thermodynamic analysis. Then, a series of experiments was performed using the test-stand. Results of these experiments are presented here, together with a model ofmultivane expanders and a thermodynamic-based method to select the working fluid. The analysis presented in this paper indicates that multivane expanders are a cheap arid mechanically simple alternative to other expansion devices proposed for small-capacity ORC systems.

Thermodynamic modelling and analysis of a solar organic Rankine cycle employing thermofluids

“…Therefore, at the given entropy and expander designed outlet pressure, 458 expander designed outlet isentropic enthalpy and isentropic specific volume can be 459 As all the unknowns in Eq. (27)(28)(29)(30) are evaluated, now the model compares the designed and 462 system operating pressure ratio values. Then, the mechanical work generated in the expander 463 and the expander efficiencies are calculated according to the conditions of under and over 464 expansion.…”

“…Following the built-in ratio of the expander, expander designed pressure ratio can be 273 calculated as [27]; 274…”

Use of Rolling Piston Expanders for Energy Regeneration in Natural Gas Pressure Reduction Stations—Selected Thermodynamic Issues

“…Nowadays, volumetric expanders are present in almost all industry branches. These machines are applied, e.g., in small and medium power organic Rankine cycle systems (ORCs) [11][12][13][14][15] and as pneumatic engines in mining or automotive industry [16]. The general advantages of volumetric expanders compared to turbines are [15] Rolling piston expanders are especially promising for natural gas pressure reduction.…”

“…The cross sectional area can be determined using the calculation procedure valid for multi-vane expanders. This procedure is comprehensively described in [14,21]. The angle between Point B and Point C (see Figure 5) can be described by the equation:…”

Nowe materiały i procesy w konwersji oraz przechowywaniu energii – wybrane zagadnienia

“…Zwrócono uwagę na potencjał pły-nący z zagospodarowania odpadowej energii cieplnej silników spalinowych [50], która stanowi energię równoważną około 50% energii zawartej w użytym paliwie. Wstępne wyniki eksperymentalne z instalacji laboratoryjnej oraz opis termodynamiczny mikro-i makroukładów ORC z zastosowaniem łopatkowego ekspandera opisano w pracy [19].…”