The Experts below are selected from a list of 636 Experts worldwide ranked by ideXlab platform
Shigeru Koyama - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic assessment of high temperature heat pumps using low gwp hfo refrigerants for heat recovery
International Journal of Refrigeration-revue Internationale Du Froid, 2015Co-Authors: Chieko Kondou, Shigeru KoyamaAbstract:Abstract Reducing energy consumption by utilizing heat recovery systems has become increasingly important in industry. This paper presents an exploratory assessment of heat pump type heat recovery systems using environmentally friendly refrigerants. The coefficient of performance (COP) of 4 cycle configurations used to raise the temperature of heat media to 160 °C with a waste heat at 80 °C is calculated and compared for refrigerants R717, R365mfc, R1234ze(E), and R1234ze(Z). A multiple-stage “extraction” cycle drastically reduces the Throttling Loss and exergy Loss in the condensers, resulting in the highest COP for R1234ze(Z). A cascade cycle using R1234ze(Z) and R365mfc has a relatively high COP and provides practical benefits. Even under adverse conditions, the primary energy efficiency is greater than 1.3 when the transmission end efficiency of the electric power generation is 0.37. The assessment demonstrated that high-temperature heat pumps are a promising approach for reducing primary energy consumption for industrial applications.
Jing Yang - One of the best experts on this subject based on the ideXlab platform.
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a novel hydraulic excavator boom driving system with high efficiency and potential energy regeneration capability
Energy Conversion and Management, 2018Co-Authors: Long Quan, Xiaogang Zhang, Jing YangAbstract:Abstract This paper proposes a new hydraulic excavator boom driving system using novel asymmetric pump to reduce energy consumption. Due to large Throttling Loss and gravitational potential wasting, conventional hydraulic excavator boom driving system has very low energy efficiency. This paper aims to improve the energy efficiency of the hydraulic excavator by reducing Throttling Loss and regenerating potential energy directly based on a novel pump controlled system. The system under consideration utilizes a novel asymmetric pump which has three ports, of which two are connected to the hydraulic cylinder, and the other one is connected to an accumulator. Thus, this system can regenerate the potential energy directly and can basically match the unequal flow rates of the single rod cylinder. The structure and working principle of the asymmetric pump controlled single rod cylinder system are studied in depth in this paper. To better demonstrate the performance of the proposed system, the popular independent metering circuit, which has been proposed to improve the efficiency of boom system, is used as a comparison. Moreover, experimental results of the two systems have been obtained based on a real 6-ton hydraulic excavator. The boom driving system of the excavator was first modified to the independent metering circuit to conduct experiment, and afterwards was modified to the proposed system. Experimental results show that, about 82.7% of the potential energy could be regenerated and reutilized by the proposed system. Compared with the independent metering circuit, the electric power consumption of the boom system during moving-up operation can be reduced by 76.1%. Furthermore, if the energy efficiency of the power source is considered, the energy consumption during the entire boom cylinder working cycle can be reduced by 75.0%. Finally, it is worth noting that the proposed system can be applied in all kinds of heavy-duty construction machineries, though only hydraulic excavator is experimented.
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efficiency improvement and evaluation of electric hydraulic excavator with speed and displacement variable pump
Energy Conversion and Management, 2017Co-Authors: Long Quan, Xiaogang Zhang, Bin Zhao, Jing YangAbstract:Abstract Hydraulic excavator driven by an internal-combustion engine is widely used in the construction field. However, some problems, such as high pollutant emissions, noise and low efficiency, exist universally. To address these problems, an electric hydraulic excavator configuration combining with an independent metering in and metering out system is proposed to improve the overall energy efficiency. In this paper, a displacement variable pump driven by a speed variable electric motor is used as power source, and a matching method based on the segmented speed and continuous displacement control of the pump is proposed to meet the requirements of high dynamic, high energy efficiency and zero emission of hydraulic excavator under different working conditions. Then, an independent metering in and metering out system is employed to reduce Throttling Loss. A test rig with a 6-ton hydraulic excavator was built up and used to validate the proposed scheme. The energy consumption characteristics of the electro-hydraulic power source under different rotational speeds and different loads are further investigated to provide analytical and experimental references for control strategy designing. Furthermore, the working performance and energy distributions of the excavator with the pure displacement variable concept, and speed and displacement variable concept are studied comparatively. Results show that, compared with pure displacement variable concept, the electric power consumption during the idle period can be reduced from 2.05 kW to 0.7 kW, the energy saving ratio under partial load condition can be up to 33%, while it is 28.5% under digging condition.
Long Quan - One of the best experts on this subject based on the ideXlab platform.
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a novel hydraulic excavator boom driving system with high efficiency and potential energy regeneration capability
Energy Conversion and Management, 2018Co-Authors: Long Quan, Xiaogang Zhang, Jing YangAbstract:Abstract This paper proposes a new hydraulic excavator boom driving system using novel asymmetric pump to reduce energy consumption. Due to large Throttling Loss and gravitational potential wasting, conventional hydraulic excavator boom driving system has very low energy efficiency. This paper aims to improve the energy efficiency of the hydraulic excavator by reducing Throttling Loss and regenerating potential energy directly based on a novel pump controlled system. The system under consideration utilizes a novel asymmetric pump which has three ports, of which two are connected to the hydraulic cylinder, and the other one is connected to an accumulator. Thus, this system can regenerate the potential energy directly and can basically match the unequal flow rates of the single rod cylinder. The structure and working principle of the asymmetric pump controlled single rod cylinder system are studied in depth in this paper. To better demonstrate the performance of the proposed system, the popular independent metering circuit, which has been proposed to improve the efficiency of boom system, is used as a comparison. Moreover, experimental results of the two systems have been obtained based on a real 6-ton hydraulic excavator. The boom driving system of the excavator was first modified to the independent metering circuit to conduct experiment, and afterwards was modified to the proposed system. Experimental results show that, about 82.7% of the potential energy could be regenerated and reutilized by the proposed system. Compared with the independent metering circuit, the electric power consumption of the boom system during moving-up operation can be reduced by 76.1%. Furthermore, if the energy efficiency of the power source is considered, the energy consumption during the entire boom cylinder working cycle can be reduced by 75.0%. Finally, it is worth noting that the proposed system can be applied in all kinds of heavy-duty construction machineries, though only hydraulic excavator is experimented.
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efficiency improvement and evaluation of electric hydraulic excavator with speed and displacement variable pump
Energy Conversion and Management, 2017Co-Authors: Long Quan, Xiaogang Zhang, Bin Zhao, Jing YangAbstract:Abstract Hydraulic excavator driven by an internal-combustion engine is widely used in the construction field. However, some problems, such as high pollutant emissions, noise and low efficiency, exist universally. To address these problems, an electric hydraulic excavator configuration combining with an independent metering in and metering out system is proposed to improve the overall energy efficiency. In this paper, a displacement variable pump driven by a speed variable electric motor is used as power source, and a matching method based on the segmented speed and continuous displacement control of the pump is proposed to meet the requirements of high dynamic, high energy efficiency and zero emission of hydraulic excavator under different working conditions. Then, an independent metering in and metering out system is employed to reduce Throttling Loss. A test rig with a 6-ton hydraulic excavator was built up and used to validate the proposed scheme. The energy consumption characteristics of the electro-hydraulic power source under different rotational speeds and different loads are further investigated to provide analytical and experimental references for control strategy designing. Furthermore, the working performance and energy distributions of the excavator with the pure displacement variable concept, and speed and displacement variable concept are studied comparatively. Results show that, compared with pure displacement variable concept, the electric power consumption during the idle period can be reduced from 2.05 kW to 0.7 kW, the energy saving ratio under partial load condition can be up to 33%, while it is 28.5% under digging condition.
Chieko Kondou - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic assessment of high temperature heat pumps using low gwp hfo refrigerants for heat recovery
International Journal of Refrigeration-revue Internationale Du Froid, 2015Co-Authors: Chieko Kondou, Shigeru KoyamaAbstract:Abstract Reducing energy consumption by utilizing heat recovery systems has become increasingly important in industry. This paper presents an exploratory assessment of heat pump type heat recovery systems using environmentally friendly refrigerants. The coefficient of performance (COP) of 4 cycle configurations used to raise the temperature of heat media to 160 °C with a waste heat at 80 °C is calculated and compared for refrigerants R717, R365mfc, R1234ze(E), and R1234ze(Z). A multiple-stage “extraction” cycle drastically reduces the Throttling Loss and exergy Loss in the condensers, resulting in the highest COP for R1234ze(Z). A cascade cycle using R1234ze(Z) and R365mfc has a relatively high COP and provides practical benefits. Even under adverse conditions, the primary energy efficiency is greater than 1.3 when the transmission end efficiency of the electric power generation is 0.37. The assessment demonstrated that high-temperature heat pumps are a promising approach for reducing primary energy consumption for industrial applications.
Stefan Elbel - One of the best experts on this subject based on the ideXlab platform.
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mathematical modeling and thermodynamic investigation of the use of two phase ejectors for work recovery and liquid recirculation in refrigeration cycles
International Journal of Refrigeration-revue Internationale Du Froid, 2015Co-Authors: Neal Lawrence, Stefan ElbelAbstract:This paper presents the results of a numerical investigation on the performance of ejector cycles in which the work recovered is used to recirculate liquid through the evaporator. The ejector recirculation cycle, in which the ejector is only used to recirculate liquid and improve evaporator performance, and the standard ejector cycle, in which the ejector can be used to both recirculate liquid and directly unload the compressor, are investigated. The analysis uses a microchannel evaporator and refrigerants R134a, R410A, and CO2. It is seen that fluids that have large Throttling Loss but gain little benefit from liquid recirculation (CO2) should use the ejector to directly unload the compressor, while fluids that have lower Throttling Loss but gain significant benefit from liquid recirculation (R134a) should use the ejector to improve evaporator performance through liquid recirculation. It is also seen that the ejector recirculation cycle is better suited for ejector off-design operation.
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Analysis and Comparison of Two-Phase Ejector Performance Metrics for R134a and CO2 Ejectors
2014Co-Authors: Neal Lawrence, Stefan ElbelAbstract:Two-phase ejectors have been gaining increased attention in recent years due to their ability to directly improve the COP of the cycle. Of common interest in two-phase ejector studies is how the ejector improves cycle COP. However, less emphasis is often given to the performance of the two-phase ejector itself. The amount of COP improvement offered by an ejector cycle is very strongly influenced by the performance of the two-phase ejector; thus, it is important to understand the operation and performance of the two-phase ejector. Defining the performance of a two-phase ejector is not as straightforward as for an isentropic expander because there are multiple fluid streams in an ejector and because it is difficult to obtain flow properties at some locations in the ejector. As a result, there are a variety of performance metrics that have been proposed for use with ejectors in general and specifically for two-phase ejectors. In the present study, several different metrics that have been proposed for measuring the performance of ejectors are presented and analyzed. Performance metrics that were originally proposed for single-phase ejectors as well as those proposed specifically for two-phase ejectors are both considered. A simple numerical ejector model is used to simulate ejector operation and calculate the performance of the ejector based on the various performance metrics. The various ejector performance metrics are then compared based on the numerical results. Experimental data for R134a and CO2 two-phase ejectors is also presented, and the ejector performance metrics are compared based on the available experimental data as well. It is seen that R134a and CO2 offer somewhat similar ejector performance, though the CO2 ejector does seem to have noticeably better performance. CO2 has significantly higher Throttling Loss than R134a, meaning that there is more work available for the two-phase ejector to recover with CO2 and larger potential COP improvement for a CO2 cycle.