| 1. |
- Rijpkema, Jelmer Johannes, 1982, et al.
(author)
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Combining Low- and High-Temperature Heat Sources in a Heavy Duty Diesel Engine for Maximum Waste Heat Recovery Using Rankine and Flash Cycles
- 2018
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In: Energy and Thermal Management, Air-Conditioning, and Waste Heat Utilization. - Cham : Springer International Publishing. - 9783030008192 ; 2nd ETA Conference, s. 154-171
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Conference paper (peer-reviewed)abstract
- Waste heat recovery (WHR) systems enable the heat losses of an engine to be captured and converted to power, thereby increasing engine efficiency. This paper aims to identify the combination of working fluid and thermodynamic cycle that yields the best WHR performance for the most important engine operating points of a heavy duty Diesel engine. WHR cycles were simulated using two distinct configurations of the heat sources available in a typical heavy duty Diesel engine: Conf-1: CAC-Coolant-Exhaust-EGRC and Conf-2: CAC-Exhaust-EGRC. Simulations were performed for fifty working fluids and four thermodynamic cycles, with and without a recuperator: the organic Rankine cycle (ORC), the transcritical Rankine cycle (TRC), the trilateral flash cycle (TFC), and the organic flash cycle (OFC). An analysis of a 100kW operating point revealed important performance differences between the two heat exchanger configurations, with maximum net power outputs of 5–7 kW for the ORC and TRC, 3–5 kW for the TFC, and 0.5–4 kW for the OFC. The use of a recuperator increased the net power output by 15 to 25% for Conf-1 and helped reduce the condenser load for Conf-2. For the dominant engine operating points of long haul cycle, the best performance was achieved for Conf-2. With this configuration, the ORC and TRC showed maximum power outputs with acetone, methanol, cyclopentane, ethanol or isohexane as the optimum working fluid.
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| 2. |
- Rijpkema, Jelmer Johannes, 1982, et al.
(author)
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Exhaust waste heat recovery from a heavy-duty truck engine: Experiments and simulations
- 2022
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In: Energy. - : Elsevier BV. - 0360-5442. ; 238
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Journal article (peer-reviewed)abstract
- Waste heat recovery using an (organic) Rankine cycle is an important and promising technology for improving engine efficiency and thereby reducing the CO2 emissions due to heavy-duty transport. Experiments were performed using a Rankine cycle with water for waste heat recovery from the exhaust gases of a heavy-duty Diesel engine. The experimental results were used to calibrate and validate steady-state models of the main components in the cycle: the pump, pump bypass valve, evaporator, expander, and condenser. Simulations were performed to evaluate the cycle performance over a wide range of engine operating conditions using three working fluids: water, cyclopentane, and ethanol. Additionally, cycle simulations were performed for these working fluids over a typical long haul truck driving cycle. The predicted net power output with water as the working fluid varied between 0.5 and 5.7 kW, where the optimal expander speed was dependent on the engine operating point. The net power output for simulations with cyclopentane was between 1.8 and 9.6 kW and that for ethanol was between 1.0 and 7.8 kW. Over the driving cycle, the total recovered energy was 11.2, 8.2, and 5.2 MJ for cyclopentane, ethanol, and water, respectively. These values correspond to energy recoveries of 3.4, 2.5, and 1.6%, respectively, relative to the total energy requirement of the engine. The main contribution of this paper is the presentation of experimental data on a complete Rankine cycle-based WHR system coupled to a heavy-duty engine. These results were used to validate component models for simulations, allowing for a realistic estimation of the steady-state performance under a wide range of operating conditions for this type of system.
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| 3. |
- Rijpkema, Jelmer Johannes, 1982, et al.
(author)
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Experimental investigation and modeling of a reciprocating piston expander for waste heat recovery from a truck engine
- 2021
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In: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311 .- 1873-5606. ; 186
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Journal article (peer-reviewed)abstract
- Waste heat recovery using an (organic) Rankine cycle has the capacity to significantly increase the efficiency of heavy-duty engines and thereby reduce fuel consumption and CO2 emissions. This paper evaluates a reciprocating piston expander used in a Rankine cycle for truck waste heat recovery by quantifying its performance on the basis of experimental results and simulations. The experimental results were obtained using a setup consisting of a 12.8 L heavy-duty Diesel engine connected to a Rankine cycle with water and are used to calibrate a semi-empirical expander model. At an engine power between 75 and 151 kW, this system recovered between 0.1 and 3 kW, resulting in an expander filling factor between 0.5 and 2.5, and a shaft isentropic effectiveness between 0.05 and 0.5. The calibrated model indicated that the heat loss (16%), mechanical loss (6–25%), pressure drop (13–42%), and leakage (25–75%) all contributed significantly to the expander performance loss. A simulation study with acetone, cyclopentane, ethanol, methanol, and R1233zd(E), showed that a change of working fluid significantly impacts the expander performance, with the filling factor varying between 0.5 and 2.2 and the effectiveness between 0.01 and 0.5, depending on the working fluid, expander speed, and pressure ratio. The results of the optimization of the built-in volume ratio and inlet valve timing during a typical long haul driving cycle showed that acetone and R1233zd(E) provided the highest available power around 3 kW absolute, or 2.2% relative to the engine. The main contributions of this paper are the presentation of experimental results of an engine coupled to a Rankine cycle, and the quantification of performance losses and the effect of working fluid variation using an adapted semi-empirical expander model, which allows for a selection of the working fluid and geometrical modifications giving optimal performance during a long haul driving cycle.
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| 4. |
- Rijpkema, Jelmer Johannes, 1982, et al.
(author)
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Experimental Results of a Waste Heat Recovery System with Ethanol Using Exhaust Gases of a Light-duty Engine
- 2019
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In: Proceedings of the 5th International Seminar on ORC Power Systems.
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Conference paper (peer-reviewed)abstract
- Organic Rankine cycle (ORC) waste heat recovery (WHR) systems have the potential to improve the efficiency of modern light-duty engines, especially at high-way driving conditions. This paper presents and discusses the experimental results of an engine connected to a compact ORC-WHR system with ethanol, suitable for integration in a modern passenger car. The aim is to show the added value of this ORC-WHR system for passenger cars by presenting the experimental results with the focus on the expander power output. The experimental setup consists of a Volvo Cars VEP-4 gasoline engine, which has an evaporator integrated in the exhaust pipe. During operation, one of two different states can be selected: electrical feedback (EFB) or mechanical feedback (MFB), where the expander can be either coupled to a 48V generator (EFB) or directly to the engine (MFB). Control strategies were developed to allow for operation of the system without interference of the driver. The results show that the current setup and control strategies can be successfully employed with significant expander power outputs for both MFB and EFB. The expander power outputs, similar for both states, go up to 2.5 kW, recovering 6.5% of the available exhaust energy and giving more than 5% improvement in fuel consumption.
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| 5. |
- Rijpkema, Jelmer Johannes, 1982, et al.
(author)
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Experimental study of an organic Rankine cycle with R1233zd(E) for waste heat recovery from the coolant of a heavy-duty truck engine
- 2021
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In: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 244
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Journal article (peer-reviewed)abstract
- Waste heat recovery is an effective method for improving engine efficiency. While most research on waste heat recovery from heavy-duty engines focuses on the high-temperature heat sources, this paper investigates the performance of a low-temperature system. The experimental setup features an organic Rankine cycle with R1233zd(E) as the working fluid recovering heat from the coolant of a heavy-duty Diesel engine. Experiments at multiple engine operating points indicated a maximum operating cycle pressure of 8 bar and temperature of 92 °C. Between 0.1 and 0.7 kW net shaft power was achieved with a thermodynamic efficiency between 1.1 and 1.8%, resulting in a maximum expander power of 0.7% relative to the engine power. A simple empirical model based on the experimental results indicated that approximately 0.7% of the engine's energy could be recovered during a driving cycle, rising to 1.3% if a high efficiency pump and expander are used. The main contribution of this paper lies in the presentation of the experimental setup and experimental results specifically dedicated to recovering the heat from the engine coolant, which permits realistic evaluation of the performance.
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| 6. |
- Rijpkema, Jelmer Johannes, 1982, et al.
(author)
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Thermodynamic Cycle and Working Fluid Selection for Waste Heat Recovery in a Heavy Duty Diesel Engine
- 2018
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In: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 2018-April
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Journal article (peer-reviewed)abstract
- Thermodynamic power cycles have been shown to provide an excellent method for waste heat recovery (WHR) in internal combustion engines. By capturing and reusing heat that would otherwise be lost to the environment, the efficiency of engines can be increased. This study evaluates the maximum power output of different cycles used for WHR in a heavy duty Diesel engine with a focus on working fluid selection. Typically, only high temperature heat sources are evaluated for WHR in engines, whereas this study also considers the potential of WHR from the coolant. To recover the heat, four types of power cycles were evaluated: the organic Rankine cycle (ORC), transcritical Rankine cycle, trilateral flash cycle, and organic flash cycle. This paper allows for a direct comparison of these cycles by simulating all cycles using the same boundary conditions and working fluids. To identify the best performing cycle, a large number of working fluids were evaluated with regards to the maximum power output of the power cycle for each heat source. Taking into account the constraints and boundary conditions, this study shows that the ORC gives the best performance with a power output of around 1.5 kW for the coolant, 2.5 kW for the exhaust gas recirculation cooler, and 5 kW for the exhaust with acetone, cyclopentane and methanol as the best performing working fluids.
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| 7. |
- Rijpkema, Jelmer Johannes, 1982
(author)
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Thermodynamic Cycles for Low- and High-Temperature Waste Heat Recovery from Heavy-Duty Engines
- 2021
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Doctoral thesis (other academic/artistic)abstract
- To reduce the environmental impact of heavy-duty vehicles, it is critical to reduce their CO2 emissions by improving the engine efficiency. A promising way to do this is by extracting waste heat from the engine during operation and converting it into useful work. This thesis presents a comprehensive evaluation of the performance of thermodynamic cycles for waste heat recovery from heavy-duty engines. First, by identifying the combination(s) of heat source, working fluid, and thermodynamic cycle that maximizes the performance. Then, by evaluating the performance of the most promising solutions using experimental investigations and detailed simulations. The potential for waste heat recovery was investigated with steady-state simulations considering two low-temperature and two high-temperature heat sources, a wide variety of working fluids, and four thermodynamic cycles: the organic Rankine cycle (ORC), the transcritical Rankine cycle, the trilateral flash cycle, and the organic flash cycle. The best overall performance was obtained with the ORC using acetone, benzene, cyclopentane, ethanol, or methanol as the working fluid, or with R1233zd(E), MM, or Novec649 if a non-flammable and non-toxic fluid was preferred. The engine coolant was the best performing low-temperature heat source, recovering 1.5 % of the engine power, and the exhaust gas was the best performing high-temperature heat source, recovering up to 5 %. By combining multiple heat sources in series, almost 8 % was recovered. Using a dual-loop system with the engine coolant and exhaust gas as the heat source, fuel consumption was reduced by over 5 %, rising to 9 % if the engine coolant temperature was increased to 140 C. Two test setups were constructed to experimentally investigate the performance of the simulated systems. The high-temperature setup consisted of a Rankine cycle with water using the exhaust gases as the heat source while the low-temperature setup recovered heat from the engine coolant using an ORC with R1233zd(E) as the working fluid. Based on the experimental findings, models of both setups were developed to predict their performance over a driving cycle. The low-temperature system was able to recover 0.73 % of the total energy required by the engine, while the high-temperature system could recover 3.37 %.
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| 8. |
- Rijpkema, Jelmer Johannes, 1982, et al.
(author)
-
Thermodynamic potential of Rankine and flash cycles for waste heat recovery in a heavy duty Diesel engine
- 2017
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In: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 129, s. 746-753
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Conference paper (peer-reviewed)abstract
- In heavy duty Diesel engines more than 50% of the fuel energy is not converted to brake power, but is lost as heat. One promising way to recapture a portion of this heat and convert it to power is by using thermodynamic power cycles. Using the heavy duty Diesel engine as the waste heat source, this paper evaluates and compares the thermodynamic potential of different working fluids in four power cycles: the Rankine cycle (RC), the transcritical Rankine cycle (TRC), the trilateral flash cycle (TFC) and the single flash cycle (SFC). To establish the heat input into the cycle, operating conditions from an actual heavy duty Diesel engine are used as boundary conditions for the cycle heat source. A GT-Power model of the engine was previously developed and experimentally validated for the stationary points in the European Stationary Cycle (ESC). An energy analysis of this engine revealed that it has four heat sources with the potential for waste heat recovery: the charge air cooler (CAC), the coolant flow, the exhaust gas recirculation cooler (EGRC), and the exhaust flow. Using fixed heat input conditions determined by the selected engine operating mode, the TFC performed best for the CAC with a net power increase of around 2 kW, while the RC performed best for the coolant flow, with a net power increase of 5 kW. For the EGRC, ethanol performed especially well with both the RC and TRC, leading to an 8 kW net power increase. When using the exhaust as heat source, all four cycles provided a power output of around 5 kW with some variation depending on the working fluid. This study shows that for most cases, considering the different heat sources, the choice of cycle has a larger impact on the cycle performance than the choice of working fluid.
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| 9. |
- Rijpkema, Jelmer Johannes, 1982, et al.
(author)
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Thermodynamic potential of twelve working fluids in Rankine and flash cycles for waste heat recovery in heavy duty diesel engines
- 2018
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In: Energy. - : Elsevier BV. - 0360-5442. ; 160, s. 996-1007
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Journal article (peer-reviewed)abstract
- A promising method to improve the efficiency of internal combustion engines is the use of thermodynamic cycles for waste heat recovery (WHR). In this study twelve working fluids are evaluated with regards to their thermodynamic potential for four cycles: the Rankine cycle (RC), the transcritical Rankine cycle (TRC), the trilateral flash cycle (TFC) and the single flash cycle (SFC). An energy and exergy analysis of a heavy duty Diesel engine revealed four sources with potential for WHR: the charge air cooler (CAC), the engine coolant, the exhaust gas recirculation cooler (EGRC) and the exhaust gas. Simulations performed for one engine operating mode, showed that the TFC performed best for the CAC with a power output of 2 kW. Owing to the thermal match between source and cycle, the RC outperformed all other cycles for the coolant with a power output of 5 kW. For the EGRC, the TRC with methanol gave the best output of 8 kW. As for the exhaust, all cycles had an output of around 6 kW with much variation between the fluids. A sensitivity analysis of the condensation temperature, source outlet temperature, degree of superheating, operating mode and expander efficiency showed significant impact on the output.
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| 10. |
- Rijpkema, Jelmer Johannes, 1982
(author)
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Waste Heat Recovery in Heavy Duty Diesel Engines
- 2018
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Licentiate thesis (other academic/artistic)abstract
- Over 50% of the energy released by burning fuel in a truck engine is lost as heat rather than being used to propel the vehicle. A promising method for capturing and reusing this heat, and thereby improving engine efficiency, is to exploit thermodynamic cycles for waste heat recovery (WHR). The goal of this thesis is to evaluate the thermodynamic performance of multiple thermodynamic cycles using many different working fluids, considering all relevant low- and high-temperature heat sources available in a heavy duty Diesel engine to be able to identify the best possible combination of heat source, working fluid and thermodynamic cycle. To evaluate the potential of each heat source, the operating conditions of a real heavy duty Diesel engine were used to define boundary conditions. A GT-Power model of such an engine was previously developed and experimentally validated for the stationary points of the European stationary cycle (ESC). Using the results from this model, an energy and exergy analysis was performed, which revealed four heat sources with the potential for waste heat recovery: the charge air cooler (CAC), the coolant flow, the exhaust gas recirculation cooler (EGRC), and the exhaust flow. Modelica models were developed for four different thermodynamic cycles: the organic Rankine cycle (ORC), the transcritical Rankine cycle (TRC), the trilateral flash cycle (TFC), and the organic flash cycle (OFC). Simulations with different boundary conditions, constraints, and engine operating conditions showed that variation in these conditions significantly affected the results obtained. In general, the best WHR performance was achieved when the thermal profiles of heat source and the chosen thermodynamic cycle were closely matched. Using realistic constraints and boundary conditions, the ORC gave the best performance with acetone, cyclopentane, or methanol as the working fluid. However, taking flammability and toxicity into account, the best-performing fluids were R1233zd(E), MM, and Novec649.
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