Experimental and Numerical Analyses on the Rotary Vane Expander Operating Conditions in a Micro Organic Rankine Cycle System

Abstract

Micro (0.5-10 kW) organic Rankine cycle (ORC) power systems are nowadays considered for domestic power generation. Selection of a suitable expander is one of the most important problems connected with the domestic ORC system design. Volumetric machines or micro-turbines can be adopted as an expander in domestic ORC systems. Scroll and screw expanders are a common choice and were successfully applied in different small-and micro-power applications. However, micro-turbines as well as scroll and screw expanders are mechanically complicated and expensive. An alternative are rotary-vane machines, which are simple and cheap compared to micro-turbines. This paper documents a study providing the experimental and numerical analyses on the rotary vane expander operating conditions in a micro-ORC system. A test-stand was designed and set up and a series of experiments was performed using the test-stand. Results of these experiments were further used as an input to numerical simulations of an expander operation. In order to simulate the expander operating conditions, a three-dimensional numerical model has been prepared. The analysis presented in this paper indicates that a properly designed multi-vane expander is a cheap and mechanically simple alternative to other expansion devices proposed for domestic ORC systems.

Numerical modelling of multi-vane expander operating conditions in ORC system

“…The experimental results showed that the expander indicated work varies in the range of 0.96-4.18 kJ/kg while its internal efficiency varies in the range of 17.2-58.3 % depending on the experimental conditions. The more detailed description of the experiment and experimental results is presented in [3]. The results from the experiment were in a good agreement with the numerical predictions so the model was validated for a given range of temperature and pressure parameters.…”

“…Presented curves show a standard variation except the strange recompression effect which is visible in the vicinity of φ = 200°. This behaviour stems from the improper construction of the expander and it was described in detail in [3]. This effect is more visible for working fluids with a higher saturation pressure and it results in decrease of efficiency of the expander.…”

“…2 shows a general view of the expander. Detailed description of the expander is presented in [3]. In order to obtain the experimental data needed for validation of expanders' numerical model, a series of experiments with varied measurement conditions were carried out using the test-stand.…”

Hybrid Electric Vehicle Performance with Organic Rankine Cycle Waste Heat Recovery System

“…Theoretically, the ORC systems can offer several benefits to the whole powertrain configuration; at best, power output of the powertrain can be increased by a maximum of approximately 15% depending on the application [26][27][28]. As a consequence of the increased efficiency of the engine, the fuel consumption can be decreased, making the ORC systems desirable for various applications [1,9,29]. Furthermore, a significant advantage of the ORC systems is that they do not depend on the pressure of the exhaust gases, as the only thing that affects the efficiency of the system are the exhaust gas temperature and mass flow rate.…”

Thermo-economic assessment of small-scale organic Rankine cycle for low-grade industrial waste heat recovery based on an experimental application

“…For instance, Kolasiński et al [88] proposed the use of vane and lobe expanders as suitable rotary alternatives to scroll machines in micro-scale applications. With regard to the range of smallscale systems, the twin-screw expander was pointed in the literature as the best candidate [89].…”