Evaluating Applicability of a Scroll Expander for CO2 Refrigeration System at Warm Climate

Simarpreet Singh,M. S. Dasgupta 대한설비공학회 2017 International Journal Of Air-Conditioning and Refr Vol.25 No.2

Performance of a trans-critical CO2 refrigeration cycle equipped with a scroll work recovery expander is investigated using a semi-empirical model of the scroll, for high ambient temperature application. Maximum isentropic efficiency of 61% is obtained, for a pressure ratio of about 3.7 for the scroll expander. Simulation results obtained are further validated against the reported experimental results. It is also observed that, about 20% of the total energy consumed can be recovered with the help of scroll expander during trans-critical operation. Based on year-round ambient temperature data, at New Delhi (India), an economic analysis is carried out for installation of work recovery scroll system. Total payback period (PBP) for scroll expanders of various capacities are also determined. It is noted that the PBP of scroll expander is about 1 to 2 years or less, which is encouraging. Total Equivalent Warming Impact (TEWI) of the system is compared with that of a conventional trans-critical CO2 refrigeration system and system running on low global warming potential (GWP) hydrofluoroolefin (R1234yf) refrigerant. Trans-critical CO2 system along with work recovery scroll expander appears justified as the same has about 15% lower TEWI compared to conventional trans-critical CO2 system but is 50% more than R1234yf system

대수나선 스크롤 유체기계 설계

문제현(Je-Hyeon Moon),이영성(Young-Sung Lee),박근태(Keun-Tae Park),김현진(Hyun-Jin Kim) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.6

A scroll expander with an algebraic scroll profile has been designed in order to study its applicability as a power converter in a R134a Rankine cycle for waste heat recovery of a passenger car with 3.5 L gasoline engine. Performance of the designed scroll expander has been calculated by numerical simulation. From waste heat recovery of exhaust gas and engine coolant over the vehicle speed of 60 km/hr∼120 km/hr, the scroll expander was calculated to produce the shaft output power of 0.61 kW∼2.6 kW, being equivalent to 6.8%∼7.9% of the engine drive power. The expander performance is quite sensitive to the clearance between fixed and orbiting scrolls. With increasing the clearance from 10 ㎛ to 20 ㎛, the expander output decreases by 12.8∼47.2%, depending on the vehicle speed, whilst it increases by 3.6∼15.8% with decreasing the clearance to 5 ㎛.

비대칭 대수나선 스크롤 팽창기 설계에 관한 연구

김현진(Hyun-Jin Kim),문제현(Je-Hyeon Moon),이영성(Young-Sung Lee) 대한설비공학회 2014 설비공학 논문집 Vol.26 No.3

In order to extract shaft power from thermal energy in a R134a Rankine cycle as waste heat recovery system of a passenger car, a scroll expander has been designed. Algebraic spiral is adopted as the base curve for scroll wrap profile in the compact scroll design. About 19% reduction in scroll diameter is accomplished when compared to the conventional involute scroll. Performance analysis on the designed scroll expander shows that the expander efficiency is 85.5% at the vehicle speed of 120 km/hr and it decreases to 67.2% at 60 km/hr, provided that the scroll clearance is kept at 10 μm. The expander can produce shaft power equivalent to about 13~14% of the driving power within the speed range of 60 ~120 km/hr.

엔진 냉각수 폐열 회수용 스크롤 팽창기 설계

김현재(Hyun Jae Kim),유제승(Je Seung Yu),김현진(Hyun Jin Kim) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6

A scroll expander was designed for an energy converter from waste heat of IC engine coolant to useful shaft work. The scroll expander is to run in a Rankine cycle which receives heat energy transferred from engine coolant circulation cycle. The working fluid was Ethanol. For axial compliance, a back pressure chamber was provided on the rear side of the orbiting scroll. Lubrication oil was delivered by a positive displacement type oil pump driven by the shaft rotation. Performance analysis on the scroll expander showed that the expander efficiency was 63.4%. It extracts shaft power of 0.6 ㎾ out of engine coolant waste heat of 17.5 ㎾, resulting in the Rankine cycle efficiency of 3.43%.

소규모 발전용 스크롤 팽창기 성능시험

김현진,박익서,라필찬 대한설비공학회 2005 설비공학 논문집 Vol.17 No.4

This paper addresses the development of a scroll expander for power generation from relatively low temperature steam source. It has a double-sided orbiting scroll member so that no thrust bearing is needed to support the base plate of the orbiting scroll. Three power transmission shafts are placed at the periphery of the orbiting scroll base plate, and these shafts can also function as anti-rotation devices. Final output is obtained from the main central shaft engaged with the three power transmission shafts through gear assembly. The clearance between the fixed and orbiting scroll elements was estimated by comparing measurement of the mass flow rate with calculation results of a computer simulation. Due to large clearance, the expander total and volumetric efficiencies were measured to be 34% and 43%, respectively. It has been shown through the computer simulation that the total and volumetric efficiencies could be improved to 65% and 83%, respectively, if the current clearance is reduced by half.

THERMODYNAMIC ANALYSIS OF A CLOSED BRAYTON/ERICSSON CYCLE ENGINE WITH SCROLL MACHINES

YOUNG MIN KIM,DONG GIL SHIN,SANG TAE LEE,DANIEL FAVRAT 대한설비공학회 2010 International Journal Of Air-Conditioning and Refr Vol.18 No.4

Stirling and Ericsson engines have great potential for many applications, including micro-cogeneration, solar power, and biomass. However, ideal cycles of both types of engines are difficult to achieve in practice because neither isothermal compression nor isothermal expansion is practical with reciprocating piston engines or with turbomachinery. On the other hand, scroll compressor and expander can be very suitable for effective cooling and heating because of the high area-to-volume ratio of scroll geometry or the application of two-phase flow. To achieve quasi-isothermal compression, either a large amount of liquid is injected into the inlet of the compressor or the compressor is externally cooled by liquid. Similarly, for quasi-isothermal expansion, either hot liquid, such as thermal oil, is injected into the inlet of the expander or the expander is externally heated by a heat source. In this current study, we have undertaken a theoretical investigation of thermodynamic analyses of several kinds of scroll-type engines, in particular with regard to associated compression and expansion processes, adiabatic or quasi-isothermal processes, and the highest cycle temperature. We selected power density, or thermal efficiency, as an objective function, and then deduced optimal design parameters for the scroll-type engine.

엔진 냉각수 폐열 회수용 스크롤 팽창기 설계

유제승(Je Seung Yu),김현재(Hyun Jae Kim),김현진(Hyun Jin Kim) 대한설비공학회 2011 설비공학 논문집 Vol.23 No.12

A scroll expander was designed for an energy converter from waste heat of IC engine coolant to useful shaft work. The scroll expander is to run in a Rankine cycle which receives heat energy transferred from engine coolant circulation cycle. The working fluid was Ethanol. For axial compliance, a back pressure chamber was provided on the rear side of the orbiting scroll. Lubrication oil was delivered by a positive displacement type oil pump driven by the shaft rotation. Performance analysis on the scroll expander showed that the expander efficiency was 63.4%. It extracts shaft power of 0.6 kW out of engine coolant waste heat of 17.5 kW, resulting in the Rankine cycle efficiency of 3.43%.

Parallel-expander Organic Rankine cycle using dual expanders with different capacities

Yun, E.,Kim, D.,Lee, M.,Baek, S.,Yoon, S.Y.,Kim, K.C. Pergamon Press 2016 ENERGY Vol.113 No.-

This study reports on a parallel-expander Organic Rankine cycle (PE-ORC) using dual expanders with different capacities. This system is applicable to waste heat sources that have large variation, such as distributed power plants with varying electricity demand. The test bench for the experimental investigation consists of a PE-ORC loop with two different scroll expanders, an electrical water heating system, and an air-cooled chiller. The tested performance characteristics for each operating mode are presented. The experimental results show three clearly separated operation regions with high efficiency, two possible switching points of the operating mode, and good heat recovery capability over a wider range of heat input compared to a PE-ORC system with two identical expanders. A control strategy for the system is proposed to maintain superheated state at the inlet of expander and to obtain high performance after changing the operating mode.

THERMODYNAMIC ANALYSIS OF A CLOSED BRAYTON/ERICSSON CYCLE ENGINE WITH SCROLL MACHINES

Kim, Young-Min,Shin, Dong-Gil,Lee, Sang-Tae,Favrat, Daniel The Society of Air-Conditioning and Refrigerating 2010 International Journal Of Air-Conditioning and Refr Vol.18 No.4

Stirling and Ericsson engines have great potential for many applications, including microcogeneration, solar power, and biomass. However, ideal cycles of both types of engines are difficult to achieve in practice because neither isothermal compression nor isothermal expansion is practical with reciprocating piston engines or with turbomachinery. On the other hand, scroll compressor and expander can be very suitable for effective cooling and heating because of the high area-to-volume ratio of scroll geometry or the application of two-phase flow. To achieve quasiisothermal compression, either a large amount of liquid is injected into the inlet of the compressor or the compressor is externally cooled by liquid. Similarly, for quasi-isothermal expansion, either hot liquid, such as thermal oil, is injected into the inlet of the expander or the expander is externally heated by a heat source. In this current study, we have undertaken a theoretical investigation of thermodynamic analyses of several kinds of scroll-type engines, in particular with regard to associated compression and expansion processes, adiabatic or quasi-isothermal processes, and the highest cycle temperature. We selected power density, or thermal efficiency, as an objective function, and then deduced optimal design parameters for the scroll-type engine.

태양열 발전용 스크롤 방식 외연기관의 열역학적 특성 연구

김영민(Young Min Kim),신동길(Dong Gil Shin),이상태(Sang Tae Lee),김현진(Hyun Jin Kim) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-

Stirling and Ericsson engines each have great potential for solar power. However, ideal cycles of both types of engines are difficult to achieve in practice because neither isothermal compression nor isothermal expansion is practical with reciprocating piston engines or with turbomachinery. On the other hand, scroll compressor and expander can be very suitable for effective cooling and heating because of the high area-to-volume ratio of scroll geometry or the application of two-phase flow. In this current study, we have undertaken a theoretical investigation of thermodynamic analyses of several kinds of scroll-type heat engines, in particular with regard to associated compression and expansion processes, adiabatic or quasi-isothermal processes, and the highest cycle temperature. We selected power density, or thermal efficiency, as an objective function, and then deduced optimal design parameters for the scroll-type heat engine. We identified CO₂ as a promising working fluid because of the reduced compression work around the critical point of CO₂.