Pumped thermal energy storage with heat pump-ORC-systems: Comparison of latent and sensible thermal storages for various fluids

Eppinger, Bernd; Zigan, Lars; Karl, Jürgen; Will, Stefan

doi:10.1016/j.apenergy.2020.115940

Cited by 64 publications

(18 citation statements)

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“…Based on the previous research of Eppinger et al conducted in 2019 [25] and in 2020 [24], the modeled setup of the PTES consists of a heat pump and an ORC, which are connected through a sensible thermal storage. The same MATLAB code with integration of the fluid data from REFPROP was applied here.…”

Section: Methodsmentioning

confidence: 99%

“…Figure 1 shows a schematic thermodynamic cycle of both processes including their state points T, s-diagram, as well as the charging and discharging of the thermal storage with its temperature profile. Further details are given in reference [24]. 1-2 superheating with internal heat exchanger (HX) 9-10 pressure change via feed pump 2-3 compression of superheated vapor 10-11 preheating in the internal HX 3-4 desuperheating in the thermal storage HX 11-12 preheating in the thermal storage HX 4-5 condensation in the thermal storage HX 12-13 evaporation in the thermal storage HX 5-6 sub-cooling in the thermal storage HX 13-14 expansion in the working machine 6-7 sub-cooling in the internal HX 14-15 desuperheating in the internal HX 7-8 isenthalpic expansion via throttle 15-16 desuperheating in the condenser 8-1 evaporation in the waste HX 16-9 condensation in the condenser…”

Section: Combined Systemmentioning

confidence: 99%

“…For a clearer and more uniform presentation of the results, reference conditions for the simulation are chosen, which refer to the working machines of the PTES, i.e., the HP (see Table 1), the sensitive thermal storage (see Table 2) and the ORC (see Table 3). The reference case is a direct result of the optimizations of the former studies presented by Eppinger et al in 2020 [24] and the design goals of Eppinger et al in 2021 [33]. Quantities of the high-pressure side of both cycles (condensation temperature in the HP process, sub-cooling temperature in the HP process) are initial values and are calculated during the simulation to fit the chosen pinch point temperatures in both cycles.…”

Section: Reference Casementioning

confidence: 99%

“…Moreover, the working machine is operated as a compressor for the heat pump process as well as an expander in the ORC-mode. In this work, the thermal storage temperature ranged from 90 • C to 120 • C. Trans-1-chloro-3,3,3-trifluoropropene (R1233zd(E)) was used, among others, as a working medium in Eppinger et al 2020 [24]. Its physical properties were found to be favorable for increasing efficiency.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of the Part Load Behavior of Combined Heat Pump-Organic Rankine Cycle Systems

et al. 2021

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Pumped Thermal Energy Storages (PTES) are suitable for bridging temporary energy shortages, which may occur due to the utilization of renewable energy sources. A combined heat pump (HP)-Organic Rankine Cycle (ORC) system with suitable thermal storage offers a favorable way to store energy for small to medium sized applications. To address the aspect of flexibility, the part load behavior of a combined HP-ORC system, both having R1233zd(E) (Trans-1-chloro-3,3,3-trifluoropropene) as working fluid and being connected through a water filled sensible thermal energy storage, is investigated using a MATLAB code with integration of the fluid database REFPROP. The influence on the isentropic efficiency of the working machines and therefore the power to power efficiency (P2P) of the complete system is shown by variation of the mass flow and a temperature drop in the thermal storage. Further machine-specific parameters such as volumetric efficiency and internal leakage efficiency are also considered. The results show the performance characteristics of the PTES as a function of the load. While the drop in storage temperature has only slight effects on the P2P efficiency, the reduction in mass flow contributes to the biggest decrease in the efficiency. Furthermore, a simulation for dynamic load analysis of a small energy grid in a settlement is conducted to show the course of energy demand, supplied energy by photovoltaic (PV) systems, as well as the PTES performance indicators throughout an entire year. It is shown that the use of PTES is particularly useful in the period between winter and summer time, when demand and supplied photovoltaic energy are approximately equal.

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Section: Methodsmentioning

confidence: 99%

Section: Combined Systemmentioning

confidence: 99%

Section: Reference Casementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Simulation of the Part Load Behavior of Combined Heat Pump-Organic Rankine Cycle Systems

et al. 2021

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“…Another interesting idea is the use of pumped thermal energy storage, which was studied by Eppinger et al [20]. They found that the power to power storage system has a conversion efficiency of 80%, while the respective sensible storage leads to 62% storage efficiency.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Different Storage Systems for Solar-Driven Organic Rankine Cycle

Bellos

Sarakatsanis

Tzivanidis

2020

ASI

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The objective of the present work is the study of different thermal storage systems for a solar-fed organic Rankine cycle (ORC) system that operates with parabolic trough collectors. The conventional design with sensible thermal oil storage is compared with a storage configuration with thermal oil and ceramic rocks, as well as the use of latent storage with phase change materials (PCMs) is investigated. The initial system is studied parametrically, and it is properly designed to order for the cycle to have high performance. Different organic fluids are studied in the organic Rankine cycle and different rocks are investigated as storage materials. Toluene is found to be the best candidate in the cycle and ceramic rocks are found to be the best candidate energetically and financially. The final results proved that both the thermal oil–ceramic rocks and the PCM are better technologies than the simple sensible thermal oil storage. For the design with a 180 m2 collecting area and 8 m3 storage tank volume, the thermal oil–ceramic rocks design leads to 13.89% system efficiency and net present value (NPV) to 129.73 k€, the PCM storage to 13.97% and 128.66 k€, respectively, while the pure thermal oil case leads to 12.48% and 105.32 k€, respectively. Moreover, it is useful to state that when the collecting area is varied from 160 m2 to 200 m2 with the tank volume at 8 m3, the efficiency enhancement with ceramic rocks compared to pure oil ranges from 8.99% up to 12.39%, while the enhancement with PCM ranges from 7.96% to 13.26%. For the same conditions, the NPV is improved with ceramic rocks from 18.35% to 25.79%, while with PCM from 14.17% to 25.29%.

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ZeoPTES: Zeotropic Pumped Thermal Energy Storage with an Ammonia–Water Mixture as Working Fluid

Bernehed

2021

Energy Tech

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The rapid rise of renewable energy production necessitates the development of large‐scale electricity storage systems. Pumped thermal energy storage (PTES), where electricity is stored in hot and cold storage units, has recently garnered a lot of interest. Previously proposed PTES systems rely on pure fluids as working fluids in Brayton‐ or Rankine‐based power cycles. Herein, ZeoPTES, a PTES system using a zeotropic mixture of ammonia and water as working fluid, is introduced. The mixture exhibits nonisothermal evaporation and condensation, which allows utilization of industrially available sensible storage units, like water or molten salt, to store the thermal energy from these phase changes. A simulation using the REFPROP 10.0 database is written to analyze the cycle. Eight parameters are identified as having an effect on system round‐trip efficiency and 30 000 simulations with random values for these parameters are run to identify the impact of all. Although efficient compressors and expanders are necessary to reach a high power‐to‐power round‐trip efficiency, the largest system‐wide losses arise from entropy generation and thermal stream mismatch in the cold and hot side heat exchangers. Using state‐of‐the‐art microchannel heat exchangers with extremely low pinch points allows for round‐trip efficiencies in excess of 70%.

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Pumped thermal energy storage with heat pump-ORC-systems: Comparison of latent and sensible thermal storages for various fluids

Cited by 64 publications

References 50 publications

Simulation of the Part Load Behavior of Combined Heat Pump-Organic Rankine Cycle Systems

Simulation of the Part Load Behavior of Combined Heat Pump-Organic Rankine Cycle Systems

Investigation of Different Storage Systems for Solar-Driven Organic Rankine Cycle

ZeoPTES: Zeotropic Pumped Thermal Energy Storage with an Ammonia–Water Mixture as Working Fluid

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