Absorption Refrigeration Technology Research Articles

Review on Absorption Refrigeration Technology and Its Potential in Energy-Saving and Carbon Emission Reduction in Natural Gas and Hydrogen Liquefaction

Review on Absorption Refrigeration Technology and Its Potential in Energy-Saving and Carbon Emission Reduction in Natural Gas and Hydrogen Liquefaction

Design, analysis, and operation optimisation of a shipborne absorption refrigeration–ice thermal storage system based on waste-heat utilization

The integration of waste-driven absorption refrigeration technology into marine applications is recognized as a promising low-carbon solution. Nonetheless, its practical application does not inherently outperform electric compression technology, primarily due to the absorption system’s inherent thermal inertia and limited adjustability. This characteristic renders the system less responsive to the dynamic refrigeration requirements typically encountered on board vessels. In this study, a shipborne ammonia absorption refrigeration–ice storage system is proposed to balance the cooling load between supply and demand. To evaluate the efficiency of the integrated system for ice storage and cooling during ship sailing, key operational variables including refrigeration temperature, cooling water temperature, and generation temperature are analyzed to assess the thermal cycle performance of the system. A typical shipping route is considered for cooling operation optimisation of the absorption refrigeration–ice storage system. This paper explores four typical cooling-supply strategies and determines the operation modes for the ice storage period and the cooling period based on considerations of energy consumption, energy utilization, and economic factors. The final optimisation results indicate that the combined system has significant advantages based on energy consumption and operation cost. In comparison to compression and absorption refrigeration systems, the proposed system exhibits 52.4% and 8.31% reductions in energy consumption, respectively. Additionally, the operation costs are decreased by 12.27% and 27.41%, respectively, and the life cycle costs are lowered by 11.51% and 32.35%, respectively. The findings of this combined system can provide a technical reference for the design and operation of a ship waste-heat refrigeration system.

Compression-assisted absorption refrigeration cycle employing organic working pairs for ultra-low grade heat recovery

Solar absorption refrigeration technology is considered an ideal alternative to energy-intensive refrigerated warehouses due to its decarbonization and environmental friendliness. However, it faces challenges in competing with vapor compression refrigeration, such as high driving heat source temperature (>100°C) and a long payback period. In this paper, we address these challenges by focusing on cycle structure and working pair, and propose a compression-assisted absorption refrigeration cycle (CARC) using R32/dimethylacetamide (DMAC) as working pair. The aim is to significantly reduce driving heat source temperature by adjusting absorption pressure utilizing an auxiliary compressor, enabling the cycle to be connected to low-cost and efficient non-concentrating solar collectors, thereby effectively shortening its payback period. This cycle includes two operating modes: CARC mode powered by solar energy during the daytime and vapor compression refrigeration cycle mode driven by off-peak electricity at night, ensuring 24-hour cooling capacity for refrigerated warehouses. The results indicate that this cycle can flexibly utilize 60∼80°C solar hot water easily obtained as driving heat source and its evaporation temperature decreases to -20°C. To assess its performance benefits, a compression-assisted absorption refrigeration system is developed and implemented. By utilizing the limited roof area of a refrigerated warehouse, it can achieve an 18.2% reduction in electricity consumption and a 24.2% reduction in carbon emissions compared to the vapor compression one annually. Additionally, during peak electricity demand periods in summer, the system exhibits significant energy-saving effects, and its payback period is about 4.2 years. Ultimately, this cycle provides a viable solution for energy-saving and emission reduction in refrigerated warehouses.

Modeling and exergy-economy analysis of residential building energy supply systems combining torrefied biomass gasification and solar energy

A novel hybrid energy system driven by torrefied biomass gasification and solar energy is proposed for the first time, and their complementarity to enhance the system’s energy efficiency is analyzed and shown. The system mainly combines biomass torrefaction, biomass gasification subsystem, solar heat collection and absorption refrigeration technology. The effects of different operating parameters on the gasification products were studied. The economic analysis is carried out based on the theory of exergy economy. The results show that torrefaction pretreatment of biomass can significantly improve its fuel quality and gasification performance. With the increase of torrefied temperature, the volume fraction of CO2 and H2 decreased while the volume fraction of CH4 and CO increased. The economic analysis shows that the expected annual income is $72,735, and the investment recovery period is 2.89 years. Through the calculation of the energy-saving and environmental benefits, it can be concluded that the hybrid energy system can save 1.05 × 106 MJ of heat per year. This equates to about 358.26 tons of standard coal or a CO2 emission reduction of 550.59 tons, the participation of solar energy is conducive to the system emission reduction. By tuning the parameter sensitivity, the influence of biomass price change on the unit exergy cost of system products was more obvious.

The study of excess enthalpy for {ionic liquid + ethanol} binary systems as new working fluids in absorption refrigeration technology

Binary systems composed of phosphonium – based ionic liquid and water, or short-chain alcohols exhibit properties which render them suitable as candidates for working fluids in absorption refrigeration technology. This work presents the study of the excess enthalpy (HE) of mixing in ethanolic solutions of the following ionic liquids: 1-ethyl-1-methylpiperidinium dimethyl phosphate, [C1C2PIP][DMP], 1-ethyl-1-methyl-pyrrolidinium dimethyl phosphate, [C1C2PYR][DMP], N,N,N-triethyl-N-methylammonium dimethyl phosphate, [N1,2,2,2][DMP],1-hydroxyethyl-1-methylpyrrolidinium dimethyl phosphate, [C1C2OHPYR][DMP], 1-ehtyl-1-methylmorpholinium diethyl phosphate, [C1C2MOR][DEP], 1-ethyl-1-methylpyrrolidinium diethyl phosphate, [C1C2PYR][DEP], and 1-ethyl-3-methylimidazolium diethyl phosphate, [C1C2IM][DEP] is presented. The experiment was performed at temperature T = 298.15 K and under ambient pressure using isothermal titration calorimetry technique. This work presents the effect of the core structure of the cation and the effect of the carbon chain length in the anion of the ionic liquid on the HE value of the systems studied. Experimental HE values were correlated using Redlich – Kister type equation. The standard deviations for the correlation vary from σ = 9 J∙mol−1 for {[C1C2OHPYR][DMP] + ethanol} to 28 J∙mol−1 for {[C1C2IM][DMP] + ethanol} showing significant agreement between experimental and calculated values. The negative excess enthalpy of mixing over the entire composition range was found in each system which indicate stronger (IL - ethanol) interactions associated with hydrogen bond formation in this system, compared to (IL - IL) and (ethanol - ethanol) interactions. For each system, the minimum of the excess enthalpy of mixing was determined, which increases in the following series: [N1,2,2,2][DMP] (HE = −2645.9 J·mol−1) < [C1C2PYR] [DMP] < [C1C2IM][DEP] < [C1C2PYR][DEP] < [C1C2PIP][DMP] < [C1C2MOR][DMP] < [C1C2OHPYR][DMP] (HE = −881.5 J·mol−1). This characteristic is desirable from the point of view of the possibility of using these systems in absorption refrigeration technology.

Performance enhancement of absorption refrigeration systems: An overview

The introduction of absorption refrigeration technology addressed several significant con-cerns in the domain of energy crisis, rising cost of fossil fuel, and ecological challenges aris-ing due to the excess use of traditional compression refrigeration systems. ARS (absorption refrigeration system) is gaining popularity as a result of benefits such as the use of low-grade heat sources and environmentally acceptable low-cost working fluid pairs. However, two sig-nificant hurdles to commercial success for this technology are the often too big size of the refrigeration system and the poor performance of the system. Numerous studies have been conducted in an attempt to discover methods for improving the COP (coefficient of perfor-mance) of ARS in order to get these systems more competitive in comparison to the conven-tional compression refrigeration systems. The goal of this article is to perform a review of the literature on different methods used to enhance the COP of ARSs based on cycle layout mod-ification and working pair selection as they are the promising solutions for the enhancement of the performance of ARSs. The futuristic aspect of this technology includes the introduction of new working pairs with no corrosion to the system components, including nanoparticles to increase heat transfer rate while reducing the cost of the system. Heat recovery methods should be introduced and the efficient design of various components especially the generator and absorber are to be addressed. This technology could be combined with other refrigeration technologies while utilizing the waste heat to further improve the efficiency of ARSs.

Performance potential and optimal configuration study for low-GWP R161-DMETEG single-stage absorption refrigeration system via pinch technology

New low-GWP R161-DMETEG mixture showed its high feasibility as an alternative working pair to overcome shortcomings of traditional ones. Its internal heat recovery capacity significantly influences operating performances. To systematically explore its ideal performance potentials and heat integration principles of the traditional single-stage absorption refrigeration system (SSARS), this paper conducted the internal heat recovery optimization and derived optimal systems by establishing an approach via pinch technology as a comprehensive planning. The ideal optimal system for maximum heat recovery under different conditions was derived initially using problem tables and Q-T graphical methods. Among all DMETEG-based fluids, R161-DMETEG exhibits the highest average performance potential of approximately 0.677 and an ideal performance improvement of 108%. Subsequently, a new configuration, called MFD-SSARS, was derived using the gird method. Its actual performances and economic feasibility under different parametrical conditions and control strategies were further explored. MFD-SSARS achieves COPs between SSARS and the ideal potential, and it can flexibly adjust internal heat recovery according to varying conditions to stimulate the performance potential. MFD-SSARS maximumly improvs COPs by approximately 65.953% relative to SSARS, reaching 96.167% of its potential under basic conditions. Despite its higher total capital costs than SSARS, it showed the lowest payback period of 2.23 years, thus proving the economic feasibility. Overall, the adopted environment-friendly working pair with designed high-performance configuration of this work serves as a technical solution to overcome current limitations of traditional absorption refrigeration technologies.

Investigation of Thermodynamic Properties of Dimethyl Phosphate-Based ILs for Use as Working Fluids in Absorption Refrigeration Technology.

In the current research, the binary solution containing ionic liquid (IL), 1-ethyl-1-methylmorpholinium dimethyl phosphate ([C1C2MOR][DMP]), 1-ethyl-1-methylpiperidinium dimethyl phosphate ([C1C2PIP][DMP]), or N,N,N-triethyl-N-methylammonium dimethyl phosphate ([N1,2,2,2][DMP]) with ethanol are investigated as new working fluids for absorption refrigeration technology. The IL was mixed with ethanol, which was considered as a refrigerant. Experimental (vapor + liquid) phase equilibria (VLE) of these binary systems were measured by an ebulliometric method within a temperature range from T = (328.15 to 348.15) K with an increment of 10 K and pressures up to 90 kPa. Experimental VLE data were correlated using non-random two-liquid (NRTL) within the maximum average relative deviation of 0.45%, which confirms the effectiveness of using such a model for calculations. Each of the proposed binary systems exhibit a negative deviation from Raoult's law, which is a very important characteristic for working pairs used in absorption heat pumps or absorption refrigerators. From a technological point of view, measurements of physicochemical properties play an important role. In this research, liquid density and dynamic viscosity were determined at temperatures from T = (293.15 to 338.15) K at ambient pressure over the whole concentration range. These properties were correlated using empirical equations. From experimental density data, the excess molar volumes were determined and correlated using the Redlich-Kister type equation. Ionic liquid: [C1C2MOR][DMP] and [C1C2PIP][DMP] were synthesized and characterized using NMR analysis. The thermophysical characterization of pure ILs, including glass transition temperature (Tg) and heat capacity at the glass transition temperature (ΔgCp), was determined using the differential scanning calorimetry technique (DSC) at atmospheric pressure. In this work, the combination of basic studies on the effect of the cation structure of an ionic liquid on the properties of their solutions with ethanol and the possibility of future application of the tested systems in a viable refrigeration system are presented.

Comprehensive Analysis for State-of-the-Art Adsorption Refrigeration Technologies

With the development of science and technology, society needs more and more energy currently, and the energy utilization efficiency has become a topic that cannot be neglected. In many cases, it is still a common phenomenon in society that a large amount of energy is wasted, which may cause more fossil energy to be burned and the greenhouse effect to be strengthened. In addition to directly improving the utilization rate of energy, we can also reduce energy waste through the recovery and reuse of waste energy. Thermal energy sorption refrigeration technology, divided into adsorption refrigeration technology using solid adsorbent and absorption refrigeration technology using liquid absorbent, could utilize waste energy or low-grade heat sources for refrigeration. Through the introduction of adsorption refrigeration technology, the research and analysis of the application of solid adsorption refrigeration technology in industry, vehicles, ships and buildings, this paper introduces the basic principle and current situation of this technology, summarizes the advantages, disadvantages and development direction of adsorption refrigeration technology, and provides reference for those who do not comprehend this technology or have doubts about the scope of its use.

Proposal and investigation of a novel small-scale natural gas liquefaction process using diffusion absorption refrigeration technology

Proposal and investigation of a novel small-scale natural gas liquefaction process using diffusion absorption refrigeration technology

Performance Optimization of Power Plant Waste Heat Using H2O-LiBr Absorption Refrigerant System

This paper examines the use of waste energy in a 3x1 MW Gas Engine Power Plant (GEPP) on Bawean Island, Indonesia. The feasibility method uses water-lithium bromide (H2O-LiBr) technology as absorption refrigeration technology. In addition, bananas are also used for cold storage to overcome waste energy utilization. The cold storage is placed in the 300 m3 area with a 100 kg load capacity for a banana with a temperature of 5oC, 85% humidity, 24 hours of operation, 1292 W cooling load, and 371 TR. This system is used because it utilizes a cheap energy source that dissipates heat from gas and has no ecological hazards, such as ozone layer depletion and global warming. The exhaust gas temperature is 500oC. Moreover, cooling loads for cold storage, which are used with thermodynamic models, and consistent fluid properties, performance, and size of cold storage were also investigated. The results obtained show that higher cold storage output comes from internal factors as compared to external factors. In addition, the absorption refrigerant with Tevaporation is 5oC, capacity 403 TR and Qabsorption is 984 kW, Qgenerator is 1066 kW, Qevaporation is 1411 kW, Qcondenser is 1493 kW, with an absorption coefficient of performance (COP) of 1.32 and power consumption of 158,25 kW. Furthermore, after calculations, analysis, and field experiments, it shows that the internal factor of the cooling load is higher than the external factor sourced from bananas in the cold storage. This phenomenon occurs probably due to the product being refrigerated, following the soar cooling capacity. Thus, the waste energy in PLTGU 3x1 MW has tried to be utilized by the refrigerant absorption system.

Thermodynamic Properties of {Diethyl Phosphate-Based Ionic Liquid (1) + Ethanol (2)} Systems, Experimental Data and Correlation

In this work, three solutions consisting of ionic liquid and ethanol were considered for forward-looking use in absorption refrigeration technology. It is proposed to use the following ionic liquids as absorbents: 1-ethyl-3-methylimidazolium diethyl phosphate (abbreviated as [EMIM][DEP]), 4-ethyl-4-methylmorpholinium diethyl phosphate ([EMMOR][DEP]), and 1-ethyl-1-methyl-pyrrolidinium diethyl phosphate ([EMPYR][DEP]). Since the thermodynamic and physicochemical properties of working fluids determine the efficiency of the refrigerator while looking for alternative operating fluids, it is crucial to perform their extensive characteristics. Therefore, in this work, (vapor + liquid) phase equilibria (VLE), liquid density (ρ), and dynamic viscosity (η) were determined for the ethanolic solution of the three mentioned diethyl phosphate-based ionic liquids. The isothermal VLE was measured by an ebulliometric method within a temperature range from T = (328.15 to 348.15) K with an increment of 10 K and pressures up to 90 kPa. Non-random two-liquid (NRTL) equation with temperature-dependence parameters was used to correlate experimental data. Physicochemical properties including liquid density and dynamic viscosity were determined at temperatures from (293.15 to 338.15) K at ambient pressure over the whole concentration range. These properties were correlated using empirical equations. From experimental density and viscosity data, the excess molar volumes and the deviations from additivity were determined and correlated using the Redlich–Kister-type equation. Two of the tested ILs, [EMMOR][DEP] and [EMPYR][DEP], were synthesized and characterized using NMR analysis. The thermophysical characterizations of pure compounds, including glass transition temperature (Tg) and heat capacity at the glass transition temperature (ΔgCp), have been determined using a differential scanning calorimetry technique (DSC) at atmospheric pressure. The work presented is a combination of basic studies on the effect of the cation structure of an ionic liquid on the properties of their solutions with ethanol, with the possibility of future application of the tested systems in a viable refrigeration system.

Hybrid Ejector-Absorption Refrigeration Systems: A Review

Absorption Refrigeration Systems (ARS) are potential alternatives to direct expansion (DX) refrigeration systems. This review focused on the incorporation of an ejector into absorption refrigeration cycles to constitute Hybrid Ejector-Absorption Refrigeration Systems (HEARS). The ejector adds several advantages to the absorption refrigeration systems depending on its location in the cycle. The two prevalent configurations of HEARS are Triple pressure level (TPL-HEARS), and Low Pressure Condenser (LPC-HEARS). Previous studies revealed the preference of the latter configuration as it allows lower circulation ratios, enhances the refrigeration effect, and could achieve a COP up to 1. Moreover, LPC configuration is suitable with single, double, and variable-effect absorption systems with a COP of above unity. In turn, the TPL-HEARS notably enhances the absorption process, particularly when a variable geometry ejector is utilized. This configuration could obtain a COP around 1.1, but only with high-density refrigerant vapor. Lately, to attain the advantages of both configurations, some studies investigated the viability of adding two ejectors to the cycle. This paper meticulously reviews investigations conducted on the emerging dual ejectors-absorption refrigeration technology. This paper reveals the general performance trend and the maximum attainable COP by each type of hybrid ejector-absorption refrigeration system. DEARS and Ejector-driven absorption refrigeration systems (ED-ARS) could achieve COP that ranges between 1.2 and 1.46. The use of a flash tank and a RHE is essential in NH3/H2O HEARS. At high generator temperatures (of 120–170 °C), DEARS was found to be the system with less complexity and best performance. Nevertheless, the performance of the DEARS might drop significantly if the heat source temperature is fluctuating. Thence, the variable-effect HEARS is considered the best alternative. The capability of HEARS to be integrated with different power generation cycles is also highlighted. Finally, the review presents possible future research opportunities to improve the absorption refrigeration technology.

Thermodynamic characterization of {1-ethyl-1-methyl-pyrrolidinium dimethylphosphate, [C1C2PYR][DMP], or 1-hydroxyethyl-1-methylpyrrolidinium dimethylphosphate, [C1C2OHPYR][DMP] (1) + ethanol (2)} binary systems

In this work, {1-ethyl-1-methylpyrrolidinium dimethylphosphate, [C1C2PYR][DMP], or 1-hydroxyethyl-1-methylpyrrolidinium dimethylphosphate, [C1C2OHPYR][DMP] (1) + ethanol (2)} binary systems were studied as an alternative working pair for the absorption heat pump cycle. It is well known that the knowledge of the thermodynamic properties of the working fluid used plays a key role in the coefficients of performance values, and thus in the efficiency of the apparatus. Therefore, in this work thermodynamic and physicochemical characteristics of ethanol solutions of two dimethylphosphate-based ionic liquids are presented. The isothermal VLE was measured by an ebulliometric method within a temperature range from T = (328.15 to 348.15) K with an increment of 10 K and pressures up to 90 kPa. Experimental VLE data have been successfully correlated using the NRTL equation using temperature-dependence parameters. Additionally, experimental VLE data were tested for thermodynamic consistency using the Van Ness test. The liquid density and dynamic viscosity were determined as a function of IL's mole fraction over a wide composition range at temperature from T = (293.15 to 338.15) K with an increment of 5 K at ambient pressure. For the correlation of physicochemical properties, empirical equations were applied. From experimental density data, the excess molar volumes were determined and correlated using the Redlich – Kister type equation. Additionally, thermophysical properties of pure ILs including glass transition temperature, heat capacity at glass transition, temperature and enthalpy of (solid + solid) phase transition as well as temperature and enthalpy of melting were determined using differential scanning calorimetry (DSC) technique. Data presented in this work, compared to the available literature data for ethanolic solutions of other dimethylphosphate-based ILs, allows discussing the impact of the IL's cation structure on the presented physicochemical and thermodynamic properties. In addition, the data presented in this work were compared to data for a water solution of lithium bromide, commercially used in absorption refrigeration technology.

Experimental data on the physicochemical and thermodynamic properties of the aqueous lithium bromide modified by the addition of lithium salt

Due to the good performance in absorption systems, lithium bromide plus water solution is the most widely used working pair. The disadvantages of this system, including, in particular, the tendency to crystallize, makes it necessary to search for new solutions. Properly choosing additives to conventional lithium bromide aqueous solution to improve the performance of the cycle is an important part of the lithium bromide absorption refrigeration studies, including ours. This paper is a continuation of our comprehensive research in this area. Mixtures consisting of lithium bromide + lithium acetate + water, and lithium bromide + lithium lactate + water, and lithium bromide + lithium trifluoroacetate + water are thought to be promising alternatives to the conventional system. In this research, the influence of three lithium salts on solubility are presented. Based on solubility measurement, two additives are selected and vapour pressure, and physicochemical properties for {lithium bromide + lithium acetate, or lithium lactate + water} systems is presented. Measurements of vapor pressure, dynamic viscosity, and the liquid density are carried out over a wide range of temperatures and compositions. Empirical equations are used to correlate dynamic viscosity, and density data. Based on the comparison between experimental results presented here and literature data for.a conventional binary system, the effect of the additive on physicochemical and thermodynamic properties is characterized and the possibility of the potential application of such new ternary systems in absorption refrigeration technology is determined.

Absorption characteristics of NH3/NASCN working pair in an adiabatic absorber with structured packing

Adiabatic absorbers with structured packing are widely used in small and medium scale absorption refrigeration units. Also, ammonia-sodium thiocyanate is a considerable potential working pair for small-scale absorption refrigeration system. The present study experimentally analyzes the absorption characteristics of ammonia-sodium thiocyanate working pair in an adiabatic absorber with stainless-steel structured packing. An adiabatic absorber filled with 4 blocks of stainless-steel structured packing as well as an experimental apparatus have been carefully designed and constructed to evaluate the absorption characteristics. Through the adjustments of working conditions of absorber such as solution inlet mass flowrate, absorption pressure and solution inlet subcooling, various experimental state points are obtained at cooling water temperatures ranging from 27.3 to 33.5 °C. Contrasts of parameters characterizing absorption performance have been made under these various working conditions. In the period of present experimental research, mass transfer coefficient reaches its maximum at 4.67 × 10-6 m/s at Reynolds numbers ranging from 339 to 611. Subcooling degree of inlet solution at range of 1.7–27.1 °C is supposed to gain a linear relationship with absorption ratio while heat load with range of 1.05–3.09 kW of the absorber gains the reverse. Absorption pressure and solution inlet flowing intensity are considered to be the promotion factor for absorption process. Parameters such as pressure potential, approach to equilibrium factor have also been analyzed. According to all these experimental results, solution inlet flowing intensity, differences between vapor pressure and solution partial pressure (i.e. the core absorption driving force) are the two main factors which greatly influence the performance of absorption process. Variables such as absorption pressure, solution inlet subcooling and cooling water temperature can be rationally adjusted in order to increase the pressure difference, enhancing the absorption performance. The adiabatic absorber with structured packing also gains a relatively high-efficient absorption performance which is sufficient for the small-scale absorption refrigeration system. Otherwise, through this study, all the parameters’ data and correlations are concluded for further study of absorption technique with ammonia-sodium thiocyanate working pair, and provide references for the designing of the adiabatic absorber with structured packing. The presents study provides significant reference for advance of research of ammonia/salt absorption refrigeration technology as well as design of structured packing adiabatic absorber with ammonia-sodium thiocyanate working pair.

Proposal and parametric study of solar absorption/dual compression hybrid refrigeration system for temperature and humidity independent control application

The solar absorption refrigeration technology plays a major role in the building energy saving and emission reduction. According to the concept of energy cascade utilization, this paper proposes a novel solar absorption/dual compression hybrid refrigeration (SADC-HR) system, which consists of solar-driven single effect absorption refrigeration (SSAR) subsystem and power-driven dual-source dual-compression refrigeration (PDCR) subsystem. An air-cooled compression refrigeration (ACR) cycle is integrated with the water-cooled compression refrigeration (WCR) cycle to make up the PDCR subsystem, so as to satisfy the all-weather space cooling/heating demand. The SADC-HR system achieves the cascade production and utilization of cold energy for the temperature and humidity independent control air conditioning system. The thermodynamic model of the SADC-HR system is built to evaluate the system performance and operating parameters, and the comparisons with two conventional systems are also discussed. The results indicate that there are optimum generating temperature of 70 °C and optimum evaporating temperature of 18 °C for the SSAR subsystem to obtain the lowest power consumption at low solar intensity of 450 W/m2. The SADC-HR system also exhibits better economic performance, and its solar collector area is respectively 55.79% and 34.75% lower than that of the conventional SSAR system and solar absorption-compression cascade refrigeration (SA-CCR) system at low solar intensity of 450 W/m2. In addition, the proposed system shows the better energy-saving performance as well as a smaller environmental impact, whose power consumption is reduced by 61.47% compared with the conventional SA-CCR system at solar intensity of 800 W/m2, and the present case study demonstrates that total seasonal electricity consumption in the SADC-HR system decreases a value of 25.32% which corresponds to a decline of 21580.66 kg of CO2 emission in comparison with the conventional ACR system.

The study on the influence of glycols on the vapor pressure, density and dynamic viscosity of lithium bromide aqueous solution

This paper is a continuation of our comprehensive research on finding the most effective additive to the conventional {lithium bromide + water} system, which is commonly used in absorption refrigeration technology. Serious disadvantages of commercially used working pairs in absorption refrigeration make it necessary to modify them. Such modification can be carried out by finding and characterizing new additives to conventional systems that will improve the operation of the refrigerator, which this work relates to. The addition of a chemical compound to such a system is one of the possibilities to improve the properties of the working pair, increase the efficiency of the absorption refrigerator and eliminate their main disadvantages. The main disadvantage of {lithium bromide + water} system is the crystallization of this salt. In recent years, many compounds have been proposed as additives to this conventional system to improve the functioning of the absorption aggregate. Based on the results obtained in our previous research, we selected substances that most effectively affected the solubility of lithium bromide in water. In this work, tests on ethylene glycol, diethylene glycol, triethylene glycol, and glycerol (additive to LiBr mass fraction w2 = 0.3) which were added to the binary {LiBr (Boryta, 1970) [1] + water (Iyoki et al., 1990) [2]} system were performed. Measurements of vapor pressure, dynamic viscosity and liquid density were carried out over a wide range of temperatures and composition. Experimental VLE data were predicted using the conductor-like screening for real solvents model, COSMO-RS. Empirical equations were used to correlate dynamic viscosity and density data. Based on the comparison of results obtained in the case of ternary systems to the properties of a conventional binary system, the effect of the additive on physicochemical properties was characterized and the possibility of potential application of such new ternary systems in absorption refrigeration technology was determined.

A Review on Exergy Analysis of Solar Refrigeration Technologies

Solar energy is becoming more and more useful in the modern day life in industrial, domestic and commercial sectors, because of his cleanliness from an environmental point of view and also contributes to the reduction of greenhouse effect gases such as CO2. Exergy analysis is a thermodynamic analysis technique based on the Second Law of Thermodynamics, which provides an alternative and illuminating means of assessing and comparing processes and systems rationally and meaningfully. Exergy analysis can assist in improving and optimizing designs. In this paper, the exergy analysis of solar thermal refrigeration cyles is reviewed. A review of the research state of art of the solar absorption and adsorption refrigeration technologies is also carried out. The cycles involved in these technologies are: open, closed, continuous and intermittent cycles. An overview of mesures of merit with regard to exergy (exergetic efficiency, exergy losses, exergy improvement and exergetic coefficient of performance) is presented. Besides, an historical and chronological view is done on the development scenario of exergy analysis in the world from 1824 until 2014. The main mathematical relations for the simulation of those cycles are presented.

(Vapor + liquid) phase equilibria of an aqueous solution of bromide-based ionic liquids – measurements, correlations and application to absorption cycles

In this work, thermodynamic and physicochemical properties including (vapor + liquid) equilibria (VLE), density and dynamic viscosity of binary mixtures composed of bromide-based ionic liquid (IL) and water were measured as a function of IL mole fraction in a wide range of temperature. The aqueous solution of the following ILs: 1-ethyl-1-methylpiperidinium bromide, ethylpyridinium bromide, 1-(2-hydroxyethyl)pyridinium bromide, 1-ethyl-1-methyl-morpholinium bromide, 1-hydroxyethyl-1-methylmorpholinium bromide, and N-ethyl-N,N-dimethyl-N-hydroxyethylammonium bromide have been tested for potential applications as working fluids in absorption refrigeration technology. The isothermal VLE has been measured by an ebulliometric method within a temperature range from T = (338.15–368.15) K and pressure up to 85 kPa and correlated using Redlich-Kwong equation of state. This work is a continuation of our systematic investigation of an aqueous solution of ionic liquids as a potential working fluid in absorption refrigeration technology. The summary of this research is the modeling of the theoretical cycles using working fluids proposed in this paper. The calculated values of the coefficient of performance (COP) were compared to other ILs from available literature and {LiBr + water} system, conventionally used on the industrial scale in absorption refrigeration technology.