Heat Pump-Organic Rankine Cycle Hybrid Systems for Co/Tri-Generation Applications: A State-of-the-Art Overview

Author(s):  
Wahiba Yaïci ◽  
Evgueniy Entchev ◽  
Pouyan Talebizadeh Sardari ◽  
Michela Longo

Abstract The following paper aims to explore a heat pump’s (HP) as well as an organic Rankine cycle’s (ORC) novel combination for the development of both an efficient and low-emissions heating and cooling systems. This latest review examines both benefits and possibilities of a combined HP-ORC system. Previously, studies have explored several different combinations, such as directly-coupled and reversible combination units as well as parallel configurations units in addition to indirectly-coupled ones. Following defining aforementioned configurations, a discussion on their performance is carried out in detail. Considerations for the optimisation of the architecture, overall of such hybrid systems via utilising the same sources while also discussing heat source, sink selection and operating temperatures as well as thermal energy storage, expander/compressor units, control strategies in addition to working fluids’ selection and managing seasonal temperatures that are increasingly variable, have been identified. Additionally, the experimental studies that have been performed reveal increasingly practical obstacles as well as other areas that require more research while serving to shed light on experimental techniques, which can be applicable to this research’s area. Based upon research, it has been revealed that regional conditions including temperatures and annual weather as well as the cost of energy produce a colossal effect on such systems’ economic feasibility framework as well as partially dictating the overall system configuration’s selection. Additionally, the review disclosed how important the following elements are: 1) a greater temperature differential amid the source of heat and heat sink; 2) proper source of heat and sink selection; 3) working fluid selection; and 4) thermal storage for the maintenance of the difference. Comparatively, from the research works from the past, additional optimisation based on individual component level as well as through control strategies of either an advanced or predictive method, these produce a smaller effect and are worth performing an evaluation on economically due to them not being feasible for the current system. Lastly, based on investigated research, there are certain areas for which recommendation have been provided with regard to future research and this includes a technology configurations’ comparison for understanding different regions’ optimal system, a sensitivity analysis for understanding key system elements for both optimisation as well as design, both an investigation as well as testing carried out for available units and applicable systems that are presently available, and identifying novel use cases.

Author(s):  
C M Invernizzi ◽  
P Iora ◽  
R Sandrini

This article investigates the possibility to enhance the performance of a biomass organic Rankine cycle (ORC) plant by adding an externally fired gas turbine (EFGT), yielding a combined EFGT + ORC system. A typical ORC configuration is first modelled and validated on data available from an existing unit 1.5 MW reference plant. Then, different working fluids belonging to the methyl-substituted benzene series and linear methylpolysiloxanes have been evaluated for the ORC section on the basis of both thermodynamics considerations and design issues of the regenerator and the turbine. Results of the simulations of the combined cycle (CC) referred to a furnace size of about unit 9 MW, assuming a maximum GT inlet temperature of 800 °C, show a maximum efficiency of 23 per cent, obtained in the case where toluene is adopted as a working fluid for the bottoming section. This value is about 4 points per cent higher than the efficiency of the corresponding simple ORC. Finally, to conclude, some preliminary considerations are given regarding the techno-economic feasibility of the combined configuration, suggesting the need of a further investigation on the possible technological solution for the furnace which represents the main uncertainty in the resulting costs of the CC.


2020 ◽  
Author(s):  
Wahiba Yaïci ◽  
Evgueniy Entchev ◽  
Pouyan Talebizadeh Sardari ◽  
Michela Longo

To develop efficient and lower emission heating and cooling systems, this book chapter focuses on interests for the innovative combination of a heat pump (HP) and organic Rankine cycle (ORC) for building applications. In this state-of-the-art survey, the potentials and advantages of combined HP-ORC systems have been investigated and discussed. Past works have examined various combinations, comprising indirectly-combined as series and parallel, directly-combined units, as well as reversible combination configurations. Following describing such arrangements, their performance is discussed. Considerations for optimising the overall architecture of these combined energy systems are pinpointed using these same sources, taking into account heat source and sink selection, expander/compressor units, selection of working fluids, control strategies, operating temperatures, thermal energy storage and managing more variable seasonal temperatures. Furthermore, experimental works present further functional problems and matters needing additional research, and assist to emphasise experimental techniques that can be utilised in this field of research. Finally, from the studies surveyed, some areas for future research were recommended.


2020 ◽  
Vol 92 (1) ◽  
pp. 10906
Author(s):  
Jeroen Schoenmaker ◽  
Pâmella Gonçalves Martins ◽  
Guilherme Corsi Miranda da Silva ◽  
Julio Carlos Teixeira

Organic Rankine Cycle (ORC) systems are increasingly gaining relevance in the renewable and sustainable energy scenario. Recently our research group published a manuscript identifying a new type of thermodynamic cycle entitled Buoyancy Organic Rankine Cycle (BORC) [J. Schoenmaker, J.F.Q. Rey, K.R. Pirota, Renew. Energy 36, 999 (2011)]. In this work we present two main contributions. First, we propose a refined thermodynamic model for BORC systems accounting for the specific heat of the working fluid. Considering the refined model, the efficiencies for Pentane and Dichloromethane at temperatures up to 100 °C were estimated to be 17.2%. Second, we show a proof of concept BORC system using a 3 m tall, 0.062 m diameter polycarbonate tube as a column-fluid reservoir. We used water as a column fluid. The thermal stability and uniformity throughout the tube has been carefully simulated and verified experimentally. After the thermal parameters of the water column have been fully characterized, we developed a test body to allow an adequate assessment of the BORC-system's efficiency. We obtained 0.84% efficiency for 43.8 °C working temperature. This corresponds to 35% of the Carnot efficiency calculated for the same temperature difference. Limitations of the model and the apparatus are put into perspective, pointing directions for further developments of BORC systems.


2021 ◽  
Vol 11 (5) ◽  
pp. 1984
Author(s):  
Ramin Moradi ◽  
Emanuele Habib ◽  
Enrico Bocci ◽  
Luca Cioccolanti

Organic Rankine cycle (ORC) systems are some of the most suitable technologies to produce electricity from low-temperature waste heat. In this study, a non-regenerative, micro-scale ORC system was tested in off-design conditions using R134a as the working fluid. The experimental data were then used to tune the semi-empirical models of the main components of the system. Eventually, the models were used in a component-oriented system solver to map the system electric performance at varying operating conditions. The analysis highlighted the non-negligible impact of the plunger pump on the system performance Indeed, the experimental results showed that the low pump efficiency in the investigated operating range can lead to negative net electric power in some working conditions. For most data points, the expander and the pump isentropic efficiencies are found in the approximate ranges of 35% to 55% and 17% to 34%, respectively. Furthermore, the maximum net electric power was about 200 W with a net electric efficiency of about 1.2%, thus also stressing the importance of a proper selection of the pump for waste heat recovery applications.


2021 ◽  
pp. 1-21
Author(s):  
G.E. Pateropoulos ◽  
T.G. Efstathiadis ◽  
A.I. Kalfas

ABSTRACT The potential to recover waste heat from the exhaust gases of a turboprop engine and produce useful work through an Organic Rankine Cycle (ORC) is investigated. A thermodynamic analysis of the engine’s Brayton cycle is derived to determine the heat source available for exploitation. The aim is to use the aircraft engine fuel as the working fluid of the organic Rankine cycle in order to reduce the extra weight of the waste heat recovery system and keep the thrust-to-weight ratio as high as possible. A surrogate fuel with thermophysical properties similar to aviation gas turbine fuel is used for the ORC simulation. The evaporator design as well as the weight minimisation and safety of the suggested application are the most crucial aspects determining the feasibility of the proposed concept. The results show that there is potential in the exhaust gases to produce up to 50kW of power, corresponding to a 10.1% improvement of the overall thermal efficiency of the engine.


Author(s):  
W Gu ◽  
Y Weng ◽  
Y Wang ◽  
B Zheng

This article describes and evaluates an organic Rankine cycle (ORC) for a waste heat recovery system by both theoretical and experimental studies. Theoretical analysis of several working fluids shows that cycle efficiency is very sensitive to evaporating pressure, but insensitive to expander inlet temperature. Second law analysis was carried out using R600a as a working fluid and a flow of hot air as a heat source, which is not isothermal, along the evaporator. The result discloses that the evaporator's internal and external entropy generation is the main source of total entropy generation. The effect of the heat source temperature, evaporating pressure, and evaporator size on the entropy generation rate is also presented. The obtained useful power is directly linked to the total entropy generation rate according to the Gouy—Stodola theorem. The ORC testing system was established and operated using R600a as a working fluid and hot water as a heat source. The maximum cycle efficiency of the testing system is 5.2 per cent, and the testing result also proves that cycle efficiency is insensitive to heat source temperature, but sensitive to evaporating pressure. The entropy result also shows that internal and external entropy of the evaporator is the main source of total entropy generation.


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