Operational Optimisation of a Non-Recuperative 1-kWe Organic Rankine Cycle Engine Prototype
Several heat-to-power conversion technologies are being proposed as suitable for waste-heat recovery (WHR) applications, including thermoelectric generators, hot-air (e.g., Ericsson or Stirling) engines and vapour-cycle engines such as steam or organic Rankine cycle (ORC) power systems. The latter t...
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MDPI AG
2019-07-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/9/15/3024 |
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| author | Chinedu K. Unamba Paul Sapin Xiaoya Li Jian Song Kai Wang Gequn Shu Hua Tian Christos N. Markides |
| author_facet | Chinedu K. Unamba Paul Sapin Xiaoya Li Jian Song Kai Wang Gequn Shu Hua Tian Christos N. Markides |
| author_sort | Chinedu K. Unamba |
| collection | DOAJ |
| description | Several heat-to-power conversion technologies are being proposed as suitable for waste-heat recovery (WHR) applications, including thermoelectric generators, hot-air (e.g., Ericsson or Stirling) engines and vapour-cycle engines such as steam or organic Rankine cycle (ORC) power systems. The latter technology has demonstrated the highest efficiencies at small and intermediate scales and low to medium heat-source temperatures and is considered a suitable option for WHR in relevant applications. However, ORC systems experience variations in performance at part-load or off-design conditions, which need to be predicted accurately by empirical or physics-based models if one is to assess accurately the techno-economic potential of such ORC-WHR solutions. This paper presents results from an experimental investigation of the part-load performance of a 1-kWe ORC engine, operated with R245fa as a working fluid, with the aim of producing high-fidelity steady-state and transient data relating to the operational performance of this system. The experimental apparatus is composed of a rotary-vane pump, brazed-plate evaporator and condenser units and a scroll expander magnetically coupled to a generator with an adjustable resistive load. An electric heater is used to provide a hot oil-stream to the evaporator, supplied at three different temperatures in the current study: 100, 120 and 140 <inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>°</mo> </msup> </semantics> </math> </inline-formula>C. The optimal operating conditions, that is, pump speed and expander load, are determined at various heat-source conditions, thus resulting in a total of 124 steady-state data points used to analyse the part-load performance of the engine. A maximum thermal efficiency of 4.2 ± 0.1% is reported for a heat-source temperature of 120 <inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>°</mo> </msup> </semantics> </math> </inline-formula>C, while a maximum net power output of 508 ± 2 W is obtained for a heat-source temperature at 140 <inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>°</mo> </msup> </semantics> </math> </inline-formula>C. For a 100-<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>°</mo> </msup> </semantics> </math> </inline-formula>C heat source, a maximum exergy efficiency of 18.7 ± 0.3% is achieved. A detailed exergy analysis allows us to quantify the contribution of each component to the overall exergy destruction. The share of the evaporator, condenser and expander components are all significant for the three heat-source conditions, while the exergy destroyed in the pump is negligible by comparison (below 4%). The data can be used for the development and validation of advanced models capable of steady-state part-load and off-design performance predictions, as well as predictions of the transient/dynamic operation of ORC systems. |
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| spelling | doaj.art-e33583cdacdb4706bae19b30b24765772022-12-21T22:59:22ZengMDPI AGApplied Sciences2076-34172019-07-01915302410.3390/app9153024app9153024Operational Optimisation of a Non-Recuperative 1-kWe Organic Rankine Cycle Engine PrototypeChinedu K. Unamba0Paul Sapin1Xiaoya Li2Jian Song3Kai Wang4Gequn Shu5Hua Tian6Christos N. Markides7Clean Energy Processes (CEP) Laboratory, Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UKClean Energy Processes (CEP) Laboratory, Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UKClean Energy Processes (CEP) Laboratory, Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UKClean Energy Processes (CEP) Laboratory, Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UKClean Energy Processes (CEP) Laboratory, Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UKState Key Laboratory of Engines, Tianjin University, Tianjin 300072, ChinaState Key Laboratory of Engines, Tianjin University, Tianjin 300072, ChinaClean Energy Processes (CEP) Laboratory, Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UKSeveral heat-to-power conversion technologies are being proposed as suitable for waste-heat recovery (WHR) applications, including thermoelectric generators, hot-air (e.g., Ericsson or Stirling) engines and vapour-cycle engines such as steam or organic Rankine cycle (ORC) power systems. The latter technology has demonstrated the highest efficiencies at small and intermediate scales and low to medium heat-source temperatures and is considered a suitable option for WHR in relevant applications. However, ORC systems experience variations in performance at part-load or off-design conditions, which need to be predicted accurately by empirical or physics-based models if one is to assess accurately the techno-economic potential of such ORC-WHR solutions. This paper presents results from an experimental investigation of the part-load performance of a 1-kWe ORC engine, operated with R245fa as a working fluid, with the aim of producing high-fidelity steady-state and transient data relating to the operational performance of this system. The experimental apparatus is composed of a rotary-vane pump, brazed-plate evaporator and condenser units and a scroll expander magnetically coupled to a generator with an adjustable resistive load. An electric heater is used to provide a hot oil-stream to the evaporator, supplied at three different temperatures in the current study: 100, 120 and 140 <inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>°</mo> </msup> </semantics> </math> </inline-formula>C. The optimal operating conditions, that is, pump speed and expander load, are determined at various heat-source conditions, thus resulting in a total of 124 steady-state data points used to analyse the part-load performance of the engine. A maximum thermal efficiency of 4.2 ± 0.1% is reported for a heat-source temperature of 120 <inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>°</mo> </msup> </semantics> </math> </inline-formula>C, while a maximum net power output of 508 ± 2 W is obtained for a heat-source temperature at 140 <inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>°</mo> </msup> </semantics> </math> </inline-formula>C. For a 100-<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>°</mo> </msup> </semantics> </math> </inline-formula>C heat source, a maximum exergy efficiency of 18.7 ± 0.3% is achieved. A detailed exergy analysis allows us to quantify the contribution of each component to the overall exergy destruction. The share of the evaporator, condenser and expander components are all significant for the three heat-source conditions, while the exergy destroyed in the pump is negligible by comparison (below 4%). The data can be used for the development and validation of advanced models capable of steady-state part-load and off-design performance predictions, as well as predictions of the transient/dynamic operation of ORC systems.https://www.mdpi.com/2076-3417/9/15/3024exergy analysisexperimentlow temperatureorganic Rankine cycleORCsmall scale |
| spellingShingle | Chinedu K. Unamba Paul Sapin Xiaoya Li Jian Song Kai Wang Gequn Shu Hua Tian Christos N. Markides Operational Optimisation of a Non-Recuperative 1-kWe Organic Rankine Cycle Engine Prototype Applied Sciences exergy analysis experiment low temperature organic Rankine cycle ORC small scale |
| title | Operational Optimisation of a Non-Recuperative 1-kWe Organic Rankine Cycle Engine Prototype |
| title_full | Operational Optimisation of a Non-Recuperative 1-kWe Organic Rankine Cycle Engine Prototype |
| title_fullStr | Operational Optimisation of a Non-Recuperative 1-kWe Organic Rankine Cycle Engine Prototype |
| title_full_unstemmed | Operational Optimisation of a Non-Recuperative 1-kWe Organic Rankine Cycle Engine Prototype |
| title_short | Operational Optimisation of a Non-Recuperative 1-kWe Organic Rankine Cycle Engine Prototype |
| title_sort | operational optimisation of a non recuperative 1 kwe organic rankine cycle engine prototype |
| topic | exergy analysis experiment low temperature organic Rankine cycle ORC small scale |
| url | https://www.mdpi.com/2076-3417/9/15/3024 |
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