Heat Transfer Analysis of Regenerative Thermo-Mechanical Refrigeration System

2020 ◽  
Author(s):  
Ahmad K. Sleiti ◽  
Mohammed Al-Khawaja
Keyword(s):  
Environmental Effects ◽  
Power Efficiency ◽  
Power Plants ◽  
Internal Combustion Engines ◽  
Waste Heat ◽  
Heat Transfer Analysis ◽  
Working Fluid ◽  
Refrigeration System ◽  
Renewable Energy Resources ◽  
Working Fluids

Abstract Refrigeration systems contribute to the critical environmental concerns including global warming and ozone depletion. It is necessary to develop new systems that use renewable energy resources and waste heat to perform the cooling function with eco-friendly working fluids. This improves the energy efficiency of the power systems and minimizes the harmful effects of conventional refrigeration systems. This paper introduces an analysis of a regenerative thermo-mechanical refrigeration system that is powered with renewable heat sources (solar, geothermal) or waste heat (from internal combustion engines, gas power plants, and steam power plants). The system operates at the supercritical conditions of the working fluids. The performance of the system is evaluated based on power efficiency, the COP, and the expander-compressor diameters. Also, a number of working fluids were compared with each other based on their performance and environmental effects. There is a trade-off between high-performance fluids and their environmental effects. Using R32 as a working fluid at Th = 150 °C and Tc1 = 40 °C, the system produces a cooling capacity of 1 kW with power efficiency of 10.23%, expander diameter of 53.12 mm and compressor diameter of 75.4mm. The regenerator increases the power efficiency by about 1%. However, the size of the regenerator is small (Dr = 6.5 mm, Lr = 142 mm].

Analysis of novel regenerative thermo-mechanical refrigeration system integrated with isobaric engine

2020 ◽  
pp. 1-27
Author(s):  
Ahmad K. Sleiti ◽  
Wahib Al-Ammari ◽  
Mohammed Al-Khawaja
Keyword(s):  
Heat Source ◽  
Environmental Effects ◽  
Power Efficiency ◽  
Waste Heat ◽  
Working Fluid ◽  
Refrigeration System ◽  
Cooling Systems ◽  
Working Fluids ◽  
Source Temperature ◽  
Heat Source Temperature

Abstract Refrigerants of the conventional cooling systems contribute to global warming and ozone depletion significantly, therefore it is necessary to develop new cooling systems that use renewable energy resources and waste heat to perform the cooling function with eco-friendly working fluids. To address this, the present study introduces and analyzes a novel regenerative thermo-mechanical refrigeration system that can be powered by renewable heat sources (solar, geothermal, or waste heat). The system consists of a novel expander-compressor unit (ECU) integrated with a vapor compression refrigeration system. The integrated system operates at the higher-performance supercritical conditions of the working fluids as opposed to the lower-performance subcritical conditions. The performance of the system is evaluated based on several indicators including the power loop efficiency, the coefficient of performance (COP) of the cooling loop, and the expander-compressor diameters. Several working fluids were selected and compared for their suitability based on their performance and environmental effects. It was found that for heat source temperature below 100 °C, adding the regenerator to the system has no benefit. However, the regenerator increases the power efficiency by about 1 % for a heat source temperature above 130 °C. This was achieved with a very small size regenerator (Dr = 6.5 mm, Lr = 142 mm). Results show that there is a trade-off between high-performance fluids and their environmental effects. Using R32 as a working fluid at heat source temperature Th=150 °C and cold temperature Tc1=40 °C, the system produces a cooling capacity of 1 kW with power efficiency of 10.23 %, expander diameter of 53.12 mm, and compressor diameter of 75.4mm.

Systematic Fluid Selection for Organic Rankine Cycles and Performance Analysis for a Combined High and Low Temperature Cycle

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Maximilian Roedder ◽  
Matthias Neef ◽  
Christoph Laux ◽  
Klaus-P. Priebe
Keyword(s):  
Performance Analysis ◽  
Low Temperature ◽  
Power Plants ◽  
Waste Heat ◽  
Selection Process ◽  
Working Fluid ◽  
Temperature Cycle ◽  
Two Stage ◽  
Working Fluids ◽  
Wide Range

The organic Rankine cycle (ORC) is an established thermodynamic process that converts waste heat to electric energy. Due to the wide range of organic working fluids available the fluid selection adds an additional degree-of-freedom to the early design phase of an ORC process. Despite thermodynamic aspects such as the temperature level of the heat source, other technical, economic, and safety aspects have to be considered. For the fluid selection process in this paper, 22 criteria were identified in six main categories while distinguishing between elimination (EC) and tolerance criteria (TC). For an ORC design, the suggested method follows a practical engineering approach and can be used as a structured way to limit the number of interesting working fluids before starting a detailed performance analysis of the most promising candidates. For the first time, the selection process is applied to a two-stage reference cycle, which uses the waste heat of a large reciprocating engine for cogeneration power plants. It consists of a high temperature (HT) and a low temperature (LT) cycle in which the condensation heat of the HT cycle provides the heat input of the LT cycle. After the fluid selection process, the detailed thermodynamic cycle design is carried out with a thermodynamic design tool that also includes a database for organic working fluids. The investigated ORC cycle shows a net thermal efficiency of about 17.4% in the HT cycle with toluene as the working fluid and 6.2% in LT cycle with isobutane as the working fluid. The electric efficiency of the cogeneration plant increases from 40.4% to 46.97% with the both stages of the two-stage ORC in operation.

scholarly journals Comparison between Organic Working Fluids in order to Improve Waste Heat Recovery from Internal Combustion Engines by means of Rankine Cycle Systems

2020 ◽  
Vol 71 (1) ◽  
pp. 113-121
Author(s):  
Alexandru Racovitza ◽  
Horatiu Pop ◽  
Valentin Apostol ◽  
Tudor Prisecaru ◽  
Daniel Taban
Keyword(s):  
Thermal Efficiency ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Internal Combustion Engines ◽  
Waste Heat ◽  
Rankine Cycle ◽  
Internal Combustion ◽  
Working Fluid ◽  
Working Fluids ◽  
Cycle Systems

The present works deals with waste heat recovery from internal combustion engines using Rankine cycle systems where working fluid are organic liquids (ORC). The first part of the paper presents the ORC technology as one of the most suitable procedure for waste heat recovery from exhaust gas of internal combustion engine (ICE). The particular engine considered in the present work is a turbocharged compression ignition engine mounted on an experimental setup. The working fluids for ORC system are: isobutene, propane, RE245fa2, RE245cb2, R245fa, R236fa, R365mfc, R1233zd(E), R1234yf and R1234ze(Z). Experimental data derived from the experimental setup has been used for 40%, 55% and 70% engine load. This papers focusses on superheating increment, on thermal efficiency and on net power output, obtained with each working fluids in Rankine cycle. Results point out the superheating increment that gives the highest thermal efficiency for each working fluid. The highest thermal efficiency is achieved in case of using R1233zd(E) as working fluid. In case of using R1233zd(E) as working fluid at 40 % load of the engine, the output power of the Rankine cycle is 3.6 kW representing 6.2 %, from the rated power at this load; at 55% load it is 5.7 kW representing 6.7 % the rated power and at 70% it is 6.7 kW representing 6.5 % from the rated power. Future perspectives are given.

scholarly journals Analysis of the Issue of Recovery of Low-Potential Energy at Small-Scale Energy Facilities

2021 ◽  
Vol 19 (2) ◽  
pp. 100-106
Author(s):  
A. V. Dmitrenko ◽  
M. I. Kolpakov
Keyword(s):  
Heat Exchange ◽  
Potential Energy ◽  
Power Plants ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Hot Water ◽  
Working Fluid ◽  
Small Scale ◽  
Working Fluids ◽  
Heat Exchange Equipment

Studying the issues of recovery of low-potential energy at smallscale energy facilities allowed to show the promising character of the organic Rankine cycle (ORC) technology as a technology for recovery or conversion of low-potential energy.The most promising developments in the field of the use and recovery of waste heat are described regarding application of ORC, which is widely used in geothermal sources, hot water boilers, gas turbine plants. Due to the constantly growing diversity of working fluids, ORC can be used within a wide temperature range from 100°C to over 350°C. Also, developments are underway in the design of ORC generators to increase reliability of its individual system units, such as turbines and expanders. Based on the above factors, it can be concluded that with a deeper study of the problems of adopting ORC technologies, they can become a very promising direction in development of heat power engineering.It has been determined that the main factor hindering the widespread adoption of the ORC technology is associated with high cost of heat exchange equipment due to increased heat exchange surfaces. It is shown that design of mini power plants and energy centres based on the use of low-potential energy requires improvement of mathematical modelling methods to reliably determine operating modes and characteristics of each of the units. Methods for modelling evaporation and condensation systems, including turbines and expanders using organic low-boiling working fluids, should be considered among the methods that are highly sought after. The methods for selecting a working fluid for ORC devices also have a significant impact on characteristics of the installation determining the range of cycle operating temperatures and pressures. The solution of the above problems can lead to a reduction in the cost of heat exchange equipment, and, consequently, to a decrease in costs for design of ORC generators. 

Working Fluid Selection for a Waste Heat Recovery Organic Rankine Cycle (ORC) Applied to a Petroleum Distillation Process

2019 ◽  
Author(s):  
Sergio Peralta ◽  
Cesar Celis
Keyword(s):  
Power Plant ◽  
Physical Properties ◽  
Power Plants ◽  
Waste Heat ◽  
Selection Process ◽  
Organic Rankine Cycle ◽  
Internal Heat ◽  
Working Fluid ◽  
Working Fluids ◽  
Working Fluid Selection

Abstract This work describes a working fluid selection process for an ORC based power plant that uses as heat source waste heat from a petroleum distillation furnace. Sixteen (16) organic fluids previously considered for similar applications are analyzed based on environmental, safety and physical properties. Two different power plants layouts, a basic one and another featuring an internal heat exchanger (IHE), are analyzed. The combinations between working fluids and plant layouts seek to maximize the ORC-based power plant thermal efficiency. ORC exergy destruction and exergy efficiency are also accounted for. In this work, the close interrelation between working fluids thermo-physical properties and expander dimensionless characteristics is also assessed. The main results indicate that R245ca and R245fa are the working fluid leading to both the highest thermal (∼16%) and exergy efficiencies (∼23%), and the lowest exergy destructions (∼703 kW). Based on required properties of the selected working fluid, an axial turbine design seems to be the most appropriate ORC expander technology for the particular application discussed in this paper. The outcomes from this work will be used as the basis for the detailed design of the components of an ORC-based power plant focused on increasing the overall efficiency of petroleum distillation processes.

Designing New Cooling System for Automobiles to Get More Fuel Efficiency and Less Environment Defects

2008 ◽  
Author(s):  
Mohsen Sharifpur
Keyword(s):  
Global Warming ◽  
Hybrid Electric Vehicle ◽  
Power Plants ◽  
Internal Combustion Engines ◽  
Waste Heat ◽  
Cooling System ◽  
Warm Season ◽  
Working Fluid ◽  
Exhaust Gas ◽  
Air Conditioner

Almost all of the internal combustion engines waste a significant amount of their fuel energy from cooling system or exhaust gas. On the other hand in the warm season or regions, it needs to remove some extra heat from air conditioner radiator (condenser). This subject effects directly on global warming. Changing some part of this waste energy to shaft work (or electricity) not only has benefit in the way to find a source for hybrid automobiles but also, it has effect on global warming, fuel economy, saving natural resources and if the fuel produce CO2, less greenhouse effect and less air pollution defect could be remarkable. In this work, a new cooling system is offered that is the same as a core of boiling water (nuclear) reactors (BWR), it means a subcooled working fluid could enter to engine shell then during the heat removes from engine and exhaust gas, it will be a boiling generator (boiling heat exchange) for a smart thermodynamic cycle. In this way not only could change some parts of unused energy to work, but also it has more capability with environment. Here, it is offered this idea by using the typical engines data. The Results confirm that it can recover at least about 20% of waste heat. This new cooling system is suitable for hybrid electric vehicle (HEV) which combines a conventional propulsion system with an onboard rechargeable energy storage system. However, it can use this idea for almost the entire internal ignition engines in automobiles or somewhere that needs to remove some heat from a device, same as condensers of modified power plants or engine of ships.

Calculation and Optimization of Heat Transfer between the Low Exergy Heat Source and Organic Rankine Cycle Applied to Heat Recovery Systems

2013 ◽  
Vol 597 ◽  
pp. 45-50
Author(s):  
Sławomir Smoleń ◽  
Hendrik Boertz
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Heat Recovery ◽  
Power Plants ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Optimization Procedure ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Total System

One of the key challenges on the area of energy engineering is the system development for increasing the efficiency of primary energy conversion and use. An effective and important measure suitable for improving efficiencies of existing applications and allowing the extraction of energy from previously unsuitable sources is the Organic Rankine Cycle. Applications based on this cycle allow the use of low temperature energy sources such as waste heat from industrial applications, geothermal sources, biomass, fired power plants and micro combined heat and power systems.Working fluid selection is a major step in designing heat recovery systems based on the Organic Rankine Cycle. Within the framework of the previous original study a special tool has been elaborated in order to compare the influence of different working fluids on performance of an ORC heat recovery power plant installation. A database of a number of organic fluids has been developed. The elaborated tool should create a support by choosing an optimal working fluid for special applications and become a part of a bigger optimization procedure by different frame conditions. The main sorting criterion for the fluids is the system efficiency (resulting from the thermo-physical characteristics) and beyond that the date base contains additional information and criteria, which have to be taken into account, like environmental characteristics for safety and practical considerations.The presented work focuses on the calculation and optimization procedure related to the coupling heat source – ORC cycle. This interface is (or can be) a big source of energy but especially exergy losses. That is why the optimization of the heat transfer between the heat source and the process is (besides the ORC efficiency) of essential importance for the total system efficiency.Within the presented work the general calculation approach and some representative calculation results have been given. This procedure is a part of a complex procedure and program for Working Fluid Selection for Organic Rankine Cycle Applied to Heat Recovery Systems.

scholarly journals Exergy analysis of the Szewalski cycle with a waste heat recovery system

2015 ◽  
Vol 36 (3) ◽  
pp. 25-48 ◽  
Author(s):  
Tomasz Kowalczyk ◽  
Paweł Ziółkowski ◽  
Janusz Badur
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Power Plants ◽  
Exergy Analysis ◽  
Waste Heat ◽  
Reference Conditions ◽  
Heat Rate ◽  
Working Fluid ◽  
Regeneration System ◽  
Waste Heat Recovery System

Abstract The conversion of a waste heat energy to electricity is now becoming one of the key points to improve the energy efficiency in a process engineering. However, large losses of a low-temperature thermal energy are also present in power engineering. One of such sources of waste heat in power plants are exhaust gases at the outlet of boilers. Through usage of a waste heat regeneration system it is possible to attain a heat rate of approximately 200 MWth, under about 90 °C, for a supercritical power block of 900 MWel fuelled by a lignite. In the article, we propose to use the waste heat to improve thermal efficiency of the Szewalski binary vapour cycle. The Szewalski binary vapour cycle provides steam as the working fluid in a high temperature part of the cycle, while another fluid – organic working fluid – as the working substance substituting conventional steam over the temperature range represented by the low pressure steam expansion. In order to define in detail the efficiency of energy conversion at various stages of the proposed cycle the exergy analysis was performed. The steam cycle for reference conditions, the Szewalski binary vapour cycle as well as the Szewalski hierarchic vapour cycle cooperating with a system of waste heat recovery have been comprised.

Power Recovery From Gas Turbines: A Review of the Limitations, and an Evaluation of the Use of “Organic” Working Fluids

1970 ◽  
Author(s):  
Stephen Luchter
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Waste Heat ◽  
Power Level ◽  
Working Fluid ◽  
Working Fluids ◽  
Valuable Source ◽  
Power Recovery

Gas-turbine waste heat appears to be a valuable source of energy, yet the number of installations in which this energy is utilized is minimal. The reasons for this are reviewed and a typical nonafterburning cycle is examined for both steam and an “organic” working fluid. The power level range over which each is attractive is obtained, and the costs of each are compared on a relative basis.

scholarly journals Fluid Selection of Transcritical Rankine Cycle for Engine Waste Heat Recovery Based on Temperature Match Method

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1830
Author(s):  
Zhijian Wang ◽  
Hua Tian ◽  
Lingfeng Shi ◽  
Gequn Shu ◽  
Xianghua Kong ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Specific Heat ◽  
Waste Heat ◽  
Working Fluid ◽  
Exhaust Gas ◽  
Match Method ◽  
Working Fluids ◽  
Cold Source ◽  
Working Fluid Selection ◽  
Transfer Zone

Engines waste a major part of their fuel energy in the jacket water and exhaust gas. Transcritical Rankine cycles are a promising technology to recover the waste heat efficiently. The working fluid selection seems to be a key factor that determines the system performances. However, most of the studies are mainly devoted to compare their thermodynamic performances of various fluids and to decide what kind of properties the best-working fluid shows. In this work, an active working fluid selection instruction is proposed to deal with the temperature match between the bottoming system and cold source. The characters of ideal working fluids are summarized firstly when the temperature match method of a pinch analysis is combined. Various selected fluids are compared in thermodynamic and economic performances to verify the fluid selection instruction. It is found that when the ratio of the average specific heat in the heat transfer zone of exhaust gas to the average specific heat in the heat transfer zone of jacket water becomes higher, the irreversibility loss between the working fluid and cold source is improved. The ethanol shows the highest net power output of 25.52 kW and lowest electricity production cost of $1.97/(kWh) among candidate working fluids.

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