Experimental study on a small-scale pumpless organic Rankine cycle with R1233zd(E) as working fluid at low temperature heat source

Abstract

Summary This paper focuses on the novelty pumpless organic Rankine cycle (ORC) and its choice of working fluids. Based on the selection criteria, the refrigerant of R1233zd(E) is firstly chosen and investigated in the pumpless ORC system. In the system, the feed pump is removed, and the refrigerant flows back and forth between two heat exchangers, which act as the evaporator or condenser, respectively. The impacts of the heating water temperature and loads on the system performance are studied to find out the best operating conditions. The low‐grade heat source is simulated by an electric boiler. The temperature of the heat resource ranges from 80°C to 100°C with the interval of 5°C. The temperature of the cooling water inlet is 10°C and is kept constant. The largest average power output is 127 W under the condition of 100°C heating water with nine loads. Because the cycle efficiency with heating steam temperature of 100°C cannot be determined, the highest energy and exergy efficiencies are 3.5% and 17.1%, respectively, for heating water of 95°C with seven loads. The experimental results show that the energy and exergy efficiencies increase with the increase of the heating temperature. The power and current outputs increase when the loads increase under the condition of the constant heating water temperature, whereas the voltage output decreases meanwhile. The generating time increases when the loads increase. This phenomenon is mainly caused by the increasing evaporating pressure and decreasing condensing pressure when the loads increases.

Design and Optimization of a Radial Inflow Turbine for Use with a Low Temperature ORC

“…An ORC has been chosen as the thermodynamic cycle over other options such as flash cycles and Stirling cycles. ORCs have been widely studied for low temperature applications [14][15][16][17][18] and have high efficiency compared to other thermodynamic cycles [19]. ORCs can also operate with dry expansion (where the expansion occurs entirely as either saturated or superheated gas), which will allow the use of micro turbines [20].…”

Analysis of a cascading power cycle without electric pumps for recovering waste heat from vanadium slag

“…Later in 2013, lots of experiments were made by Yamada et al 16 to test the generation performance of the intermittent PRC system, which showed that the average output power was about 20 W. In the same year, Li et al 17 proposed a gravity-driven ORC, selecting PF5060 as working fluid, but the minimum height required for compressing was about 20.9 m. To realize the small-scale PRC, Gao et al established an intermittent PRC system with R245fa as working fluid in 2015 18 and a modified PRC system in 2018, 19 which obtained the maximum shaft power (361.0 W) at 95 C hot water temperature and the thermal efficiency range (2.4%-3.1%) at 80 C to 95 C heat source temperature. In 2019, Lu et al 20 experimentally investigated a 100 W-scale PRC. R1233zd(E) was selected as the working fluid, and the optimal energy efficiency of 3.5% and exergy efficiency of 17.1% were obtained at the heat source temperature of 95 C. In 2020, Wang et al 21 proposed a novel ammonia-water power cycle, and the working fluid was supplied to the higher-pressure side by a special component and the assistance of gravity and the cycle's internal thermal energy, which concluded that the cycle performance was improved compared with the conventional type.…”

A new power/cooling cogeneration system using R1234ze(E)/ionic liquid working fluid

“…[11][12][13][14][15][16][17][18][19][20][21][22][23] Dai et al 11 have studied the performance of ORC with 10 different working fluids in which R236ea shows the highest exergy efficiency of 35.43%; Hettiarachchi et al 12 evaluated the performance of different type of working fluids in details in an optimized ORC; Li et al 13 compared ordinary ORC and twostage ORC in detail, and the results indicate that twostage ORC can decrease the irreversible loss; Wang et al 14,15 used mixtures as the working fluid of subcritical ORC in order to get better system performance; Kalina et al 16 presented two different systems based on ORC, operational parameters, size and investment which were especially considered; Zhang et al 17 studied a kW-scale ORC to study the effects of the mass flow of working fluid and heat source; Schuster et al 18 studied the energy and exergy efficiencies of subcritical and supercritical ORC using different working fluids; Cayer et al 19 compared the performance of CO 2 , ethane and R125 as the working fluid for a transcritical ORC; Zhang et al 20 studied a R134a ORC, and the result shows that the discussed ORC has good sustainability; Uusitalo et al 21 studied the performance of hydrocarbons, fluorocarbons and siloxanes as the working fluid for subcritical ORC and analyzed the effects of their critical properties; Yi et al 22 proposed a multi-objective mathematical programming model for ORC which takes environmental impact and thermoeconomic performance into account; Wang and Fu improved the efficiency of a solar assisted cogeneration system by coupling with an ORC, and an increment of 9.87% in efficiency was obtained. 23 Wang et al 24 and Lu et al 25 conduct experimental research on the actual performances of an ORC using R601a/R600a and R1233zd as the working fluid. Li et al studied an ORC using R1234ze(E) driven by hot water at 100 C to 200 C. 26 They also focused on the dual-pressure ORC using R1234ze(E).…”