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The performance of a 300 kW organic Rankine cycle (ORC) prototype was experimentally investigated for low-grade waste heat recovery in industry. The prototype employed a specially developed single-stage radial turbine that was integrated with a semi-hermetic three-phase asynchronous generator. R245fa was selected as the working fluid and hot water was adopted to imitate the low-grade waste heat source. Under approximately constant cooling source operating conditions, variations of the ORC performance with diverse operating parameters of the heat source (including temperature and volume flow rate) were evaluated. Results revealed that the gross generating efficiency and electric power output could be improved by using a higher heat source temperature and volume flow rate. In the present experimental research, the maximum electric power output of 301 kW was achieved when the heat source temperature was 121 °C. The corresponding turbine isentropic efficiency and gross generating efficiency were up to 88.6% and 9.4%, respectively. Furthermore, the gross generating efficiency accounted for 40% of the ideal Carnot efficiency. The maximum electric power output yielded the optimum gross generating efficiency.
Ruijie Wang; Guohua Kuang; Lei Zhu; Shucheng Wang; Jingquan Zhao. Experimental Investigation of a 300 kW Organic Rankine Cycle Unit with Radial Turbine for Low-Grade Waste Heat Recovery. Entropy 2019, 21, 619 .
AMA StyleRuijie Wang, Guohua Kuang, Lei Zhu, Shucheng Wang, Jingquan Zhao. Experimental Investigation of a 300 kW Organic Rankine Cycle Unit with Radial Turbine for Low-Grade Waste Heat Recovery. Entropy. 2019; 21 (6):619.
Chicago/Turabian StyleRuijie Wang; Guohua Kuang; Lei Zhu; Shucheng Wang; Jingquan Zhao. 2019. "Experimental Investigation of a 300 kW Organic Rankine Cycle Unit with Radial Turbine for Low-Grade Waste Heat Recovery." Entropy 21, no. 6: 619.
In this study, the flow dynamics and heat transfer process of a single droplet obliquely impacting a wall covered by a thin liquid film are investigated numerically based on the volume of fluid method, with the impact angle ranging from 0° to 45°. The results show that the flow and heat transfer for the oblique impact of a droplet show asymmetric pattern and differ significantly from those for a normal impact. The asymmetric heat transfer pattern for oblique impact of a droplet primarily lied in the asymmetric influenced area caused by asymmetric crown jets spreading on the bilateral sides and asymmetric heat transfer oscillation in the valley region caused by asymmetric recirculation. These asymmetries originate indirectly from the asymmetric droplet impaction energy transfer to the bilateral liquid film induced by the oblique impact angle. In addition, parametric studies suggest that the asymmetry of the heat transfer distribution becomes more significant for a larger oblique impact angle, higher Weber number, or smaller dimensionless film thickness.
Qi Yang; X.H. Wang; L. Zhu; R.J. Wang; J.Q. Zhao. Numerical investigation of local heat transfer characteristics of an oblique droplet impacting a wetted wall. Case Studies in Thermal Engineering 2019, 14, 100461 .
AMA StyleQi Yang, X.H. Wang, L. Zhu, R.J. Wang, J.Q. Zhao. Numerical investigation of local heat transfer characteristics of an oblique droplet impacting a wetted wall. Case Studies in Thermal Engineering. 2019; 14 ():100461.
Chicago/Turabian StyleQi Yang; X.H. Wang; L. Zhu; R.J. Wang; J.Q. Zhao. 2019. "Numerical investigation of local heat transfer characteristics of an oblique droplet impacting a wetted wall." Case Studies in Thermal Engineering 14, no. : 100461.
The conjugate heat transfer of impingement jet is investigated in order to better reveal its underlying principles. The study is carried out basing on a validated CFD model of free-air-jet that discharges from a round nozzle and impinges perpendicularly onto a solid plate with uniform heat flux boundary condition on heated surface. Different operating parameters including plate thickness, plate material, jet Reynolds number and nozzle diameter are investigated. It is observed that these parameters alter the Nusselt number and the thermal condition at the fluid–solid interface. Results show that thermal conjugate effect redistributes the boundary heat flux and convert the thermal boundary from uniform heat flux condition into approximately isothermal condition. This is driven by the non-uniform distribution of thermal convection resistances on impinged surface. The strength of heat redistribution is related to both the thermal conduction resistance and thermal convection resistance. Heat flow in the conjugate heat transfer process of impingement jet is illustrated by using heat transfer network methodology, which helps better understand the process of heat redistribution and thermal boundary altering. Another focus of present work is the discrepancy of Nusselt numbers between conjugate case and non-conjugate case. It is found that the conjugate effect leads to the decay of Nusselt number. This is interpreted from the viewpoint of field synergy principle and it turns out to be a consequence of the degradation in synergy between thermal field and flow field due to thermal conjugate effect.
Xiao Wei Zhu; Lei Zhu; Jing Quan Zhao. An in-depth analysis of conjugate heat transfer process of impingement jet. International Journal of Heat and Mass Transfer 2016, 104, 1259 -1267.
AMA StyleXiao Wei Zhu, Lei Zhu, Jing Quan Zhao. An in-depth analysis of conjugate heat transfer process of impingement jet. International Journal of Heat and Mass Transfer. 2016; 104 ():1259-1267.
Chicago/Turabian StyleXiao Wei Zhu; Lei Zhu; Jing Quan Zhao. 2016. "An in-depth analysis of conjugate heat transfer process of impingement jet." International Journal of Heat and Mass Transfer 104, no. : 1259-1267.