Low-temperature Thermal Energy Research Articles

Preparation and characterization of Na2HPO4·12H2O@polymethyl methacrylate nanocapsule for efficient thermal energy storage

Hydrated salts have been considered as a promising phase change material for usage in low-temperature thermal energy storage applications; however, they suffer from poor thermal reliability, corrosiveness, and inefficient thermal storage. Nanoencapsulation is an effective approach used to improve the thermal energy storage performance and reliability of phase change materials. At present, limited studies have been conducted on the core–shell encapsulation-based hydrated salt core. In this work, an efficient method was developed for the encapsulation of Na2HPO4·12H2O into the polymethylmethacrylate (PMMA) nanocapsules. The morphology and core–shell structure of the nanocapsules were investigated using scanning electron microscope (SEM) and transmission electron microscope (TEM). The chemical composition of the nanocapsules was confirmed by Fourier transformation infrared spectroscopy (FTIR). The phase change performance of the nanocapsules was studied using a differential scanning calorimeter (DSC). Thermal cycling was adopted to reveal the thermal reliability of the nanocapsules. The corrosiveness of the nanocapsules was also investigated. In addition, the nanocapsules were combined with copper foam to prepare a novel composite phase change material (C-PCM) for efficient thermal energy storage. Results demonstrated that the melting and solidifying latent heat of the nanocapsules were 157.3 and 140.6 kJ/kg, respectively. The encapsulation ratio of the nanocapsules was 64.1 %, and 97.7 % was maintained after 500 thermal cycles. Hydrated salt nanocapsules were virtually non-corrosive to the metal. The latent heat of the composite PCM was calculated to be approximately 72.7 kJ/kg. The thermal conductivity of the composite PCM was about 1.25 W/(m·K), 5.5 times higher than that of the nanocapsules. The heat storage test showed that the time required for the heat storage of the C-PCM was reduced by about 82.8 % compared with that of the pure nanocapsules. This novel nanocapsule has high phase change properties and thermal reliability and exhibits good low-temperature thermal energy storage prospects.

Is Kalina cycle or organic Rankine cycle for industrial waste heat recovery applications? A detailed performance, economic and environment based comprehensive analysis

Contrary to the increase in energy demand throughout the world, fossil fuels, which are the main energy source, is now more difficult to reach because of the pandemic, transport or bilateral relations, etc. These obstacles in obtaining fossil fuels reveal the need to minimize energy wastage by utilizing low-temperature waste heat sources releasing the atmosphere without use. Especially for the industrial fields usage of advanced heat recovery systems is necessary. In addition, it is a remarkable point that the evaluation of low-temperature thermal energy potential will contribute significantly to the reduction of carbon emissions, which is one of the most important goals in developed and developing countries. In this study, Kalina and Organic Rankine cycles, which are the most important low-temperature energy conversion systems in the utilization of low-temperature industrial waste heat with a temperature of 250 ºC and a mass flow of 10 m/s, were examined and compared to each other in terms of energy, exergy efficiency, economic outlook, and environmental effects. During the study, the turbine inlet pressure of the Kalina cycle was selected as 60, 90 and 120 bar, while the turbine inlet pressure of the organic Rankine cycle increased from 10 bar to the critical pressure of the fluid. For all selected pressure levels, the turbine inlet temperature was increased from the saturated vapor temperature of the fluid to 240 ºC. As a result, although the Kalina cycle was found economically better than the organic Rankine cycle (3.93 years), the organic Rankine cycle using n-Pentane showed a better performance than the Kalina cycle in terms of energy, exergy, and CO2 emission reduction. The thermal efficiency, exergy efficiency, payback period, and CO2 emission reduction value of the organic Rankine cycle with n-Pentane were calculated as 25.95%, 71.77%, 4.03 years, and 207.17 kg-CO2/h, respectively.

Evaluation of thermal kinetics of microencapsulated PCM for low-temperature thermal energy storage application

In the present investigation, the microencapsulated phase change material (PCM) thermal kinetics for low-temperature thermal energy storage applications (32 °C–53 °C) is analysed. Microencapsulated PCMs selected are CaCl2·6H2O, n-Hexadecane, n-Octadecane, n-Eicosane, Capric/Lauric acid, Paraffin wax (C30H62), and Palmitic acid (C16H32O2), respectively. Ambient air is selected as the external/heat transfer fluid which interacts with PCM materials. The thermal kinetics of microencapsulated PCMs is evaluated by selecting the solid-liquid interface position with melting time and molten fraction as the performance evaluation parameters. Among all the phase change materials, the best PCM is found to be CaCl2·6H2O with 4 cm of PCM diameter, 53 °C of external fluid temperature, and 106 min of melting time.

Performance analysis of a concentrated system with series photovoltaic/thermal module and solar thermal collector integrated with PCM and TEG

This study presents a detailed performance analysis of a novel concentrated system which consists of a photovoltaic/thermal (PV/T) module with phase change material (PCM) and a solar thermal (ST) collector with thermoelectric generators (TEG) connected in series. While considerable electrical energy is acquisitive, enhanced high-temperature thermal energy is also achieved. In this system, the PV/T module generates both photoelectric power generation and low-temperature thermal energy, and the secondary heated water and the secondary thermoelectric output are obtained through the ST module and TEG on ST. Theoretical investigations find that, the system of the PV/T module and the ST module in series (PV/T-ST) performs well in terms of thermal performance and comprehensive performance. During the all-day operation, compared with the PV/T-PV/T system, the final temperature of the water tank in the PV/T-ST system is about 5 °C higher. Also, the electrical efficiency and the thermal efficiency are 10.65% and 65.22% respectively at 12:30 when using the 1.1-m2 Fresnel lens. Where, TEG converts some thermal energy into electrical energy, increasing the amount of high-grade energy of the system by about 321.53 kJ in the daytime. Additionally, the discussion from different perspectives on the impact of different parameters is also carried out.

Ultralow-temperature-driven water-based sorption refrigeration enabled by low-cost zeolite-like porous aluminophosphate

Thermally driven water-based sorption refrigeration is considered a promising strategy to realize near-zero-carbon cooling applications by addressing the urgent global climate challenge caused by conventional chlorofluorocarbon (CFC) refrigerants. However, developing cost-effective and high-performance water-sorption porous materials driven by low-temperature thermal energy is still a significant challenge. Here, we propose a zeolite-like aluminophosphate with SFO topology (EMM-8) for water-sorption-driven refrigeration. The EMM-8 is characterized by 12-membered ring channels with large accessible pore volume and exhibits high water uptake of 0.28 g·g−1 at P/P0 = 0.2, low-temperature regeneration of 65 °C, fast adsorption kinetics, remarkable hydrothermal stability, and scalable fabrication. Importantly, the water-sorption-based chiller with EMM-8 shows the potential of achieving a record coefficient of performance (COP) of 0.85 at an ultralow-driven temperature of 63 °C. The working performance makes EMM-8 a practical alternative to realize high-efficient ultra-low-temperature-driven refrigeration.

Development of lithium hydroxide-metal organic framework-derived porous carbon composite materials for efficient low temperature thermal energy storage

Lithium hydroxide based chemical heat storage (CHS) materials with high energy density and long storage periods have become the limelight of research for efficient use of low-temperature thermal energy and long-term storage. Herein, we report a novel LiOH composite CHS material with a porous carbon material derived from the zeolite imidazolate framework (ZIF-8) as supporting porous carbon matrix (ZSPCM). The Li/ZSPCM composite exhibits remarkable heat storage density up to 1373.3 kJ kg −1 with low charging temperature and good water adsorption ability owing to the large specific surface area of ZSPCM and well-dispersed small LiOH particles on it, which increase the contact between LiOH and H 2 O molecules and concomitant improvement in storage performance. In addition, the storage capacity of this composite material has no significantly degradation after 15 cycles of repeated hydration and dehydration, indicating its excellent cycle stability. And the thermal conductivity of Li/ZSPCM composite also shows a significant improvement over pristine LiOH by virtue of the outstanding thermal conductivity of the ZSPCM. This work develops a promising LiOH CHS material may sheds light on future directions for long period storage of low-temperature heat energy and the further exploitation of ZSPCM. • The chemical heat storage material based on the composite of LiOH·and porous carbon derived from ZIF-8 are developed. • Li/ZSPCM composite materials has remarkable heat storage density and good water adsorption ability. • Li/ZSPCM composite materials exhibits great cycling stability performance and significantly enhanced thermal conductivity.

Simultaneous Production of Solar Thermal Heat and Power for Industrial Applications

Currently most of the energy production is supported by fossil fuels, however, renewable sources contribution on worldwide demand of energy has been in constantly growth. One of the main challenges in the use of solar thermal energy in industrial processes is their cost, especially when is compared to energy generation by fossil fuels. This cost delimits the investment payback time for a thermo-solar installation to be feasible. This fact makes crucial the development of methodologies for the integration of solar energy for large-scale industrial applications. This work deals with the thermo-economic evaluation of the heat and power production through a low-temperature flat-plate solar collector system. Also, strategies were developed to increase energy efficiency by evaluating different process integration scenarios. The proposed strategies for energy efficiency combined with renewable energy were applied to an integrated solar thermal energy system into a 1G and 2G (first and second generation) bioethanol process from sugarcane. It was found that to replace the fully process heat and power with low-temperature solar thermal energy, a heat recovery network ? ?? ?????? of 5 °C, a heat duty of 131 kW and a supply temperature of 105 °C are required. All these results lead to a cost of 0.2112 USD/kWh of the integrated system. The power system operates independently by mean an Organic Rankine Cycle and the heating system is supplied by a solar collector network with a cost of 0.0477 USD/kWhele.

Performance optimization and experimental analysis of a novel low-temperature latent heat thermal energy storage device

Due to the continuous penetration of renewable energy in the building sector, its instability increases the importance of energy storage in balancing energy demand and supply. However, the low thermal conductivity of phase change materials limits its application. This paper proposes a shell-tube latent heat thermal energy storage device with fins to enhance heat transfer. The ANSYS software is used to establish a three-dimensional simulation model of the device, considering of the nature convection. Furthermore, for this study, an experimental platform is built, and the influence of factors on the device during the charging and discharging period is analyzed. Simulation results show that the melting effects of the device vary with the fin and tube pitch; their optimization results are 40 mm and 90 mm, respectively. Experimental results exhibit that the inlet temperature influences the storage effect of the device, but as long as the phase change material is completely melted, pursuing excessively high temperature is not necessary. The same pattern was observed with the flow rate when the heat exchange fluid reached a turbulent state. After optimization, the effective energy release efficiency of the device reaches 77%, and the corresponding inlet temperature, heat storage flow, and heat release flow are 60 °C, 0.144 m3/h, 0.288 m3/h, respectively.

Regasification of liquefied natural gas in satellite terminals: Techno-economic potential of cold recovery for boosting the efficiency of refrigerated facilities

The regasification of liquefied natural gas releases low-temperature thermal energy, which is usually wasted. Most initiatives to recover this cold mainly focus on large-scale harbour terminals rather than on small-scale applications in satellite facilities. This paper proposes a new system configuration that can be used to exploit liquefied natural gas cold as a by-product of regasification in satellite plants supplying sub-zero refrigeration in agro-food industries. Cold is applied indirectly to lower the condensation temperature of the vapour-compression chillers which handle the thermal load of cold rooms. The system seeks to boost efficiency, an effect that would be more marked in warm climates. Performance is best when the peak refrigeration load matches the maximum cold thermal energy available from the regasification site. When this is the case, the annual electricity saving is 9–22% more than when a conventional refrigeration system is used with wet cooling towers and with no liquefied natural gas cold recovery. The economic potential of the system is assessed with a Monte Carlo analysis. The cost of producing refrigeration throughout the system’s lifetime can be reduced by 5–15% with respect to the conventional reference system in warm/temperate locations and for large/medium plant sizes. However, the system is no so competitive in economic terms for cold locations and small-size plants.

Assessing the suitability of alkali-activated metakaolin geopolymer for thermochemical heat storage

This study investigates the suitability and potentials of using alkali-activated metakaolin geopolymers as sustainable low-cost thermochemical heat storage materials via water sorption and/or hydration reactions. Four different alkali-activated metakaolin geopolymer formulations were assessed. The cyclic water sorption capacity and moisture diffusion coefficients were assessed via two continuous water vapor sorption/desorption cycles using the dynamic water vapor sorption (DVS), proving the regeneration ability of geopolymers for sorption thermal energy storage. The thermochemical properties of geopolymers, including the dehydration enthalpy and activation energy, were determined. For the amorphous sodium aluminosilicate hydrate gel (N-A-S-H) with bulk Si/Al ratio of 1.5, the mass and volumetric energy storage capacity of 827.9 J/ghydrate sample and 350 kW h/m3 were achieved, with a charging temperature of around 120 °C. The outcomes of this study suggest that alkali-activated metakaolin geopolymers have the potential to be used for both low-temperature water sorption thermal energy storage and medium temperature hydration/dehydration thermochemical energy storage. The energy storage performances of metakaolin geopolymers are closely related to their aluminosilicate framework structures and surface textural properties. The partial crystallisation of the amorphous N(K)-A-S-H gel, resulting in the formation of micropores, which does not seem to affect the maximal water uptake but increases the proportion of the chemically bound water. The presence of the amorphous mesoporous aluminosilicate gel N(K)-A-S-H gel in geopolymers leads to desorption hysteresis at relative humidity higher than 30 %. Further optimisation of the synthesis approach, aluminosilicate framework structures, micro and mesopore structures will be required to optimise their overall thermal energy storage performances.

Spectral-splitting hybrid PV-thermal (PV-T) solar collectors employing semi-transparent solar cells as optical filters

Spectral splitting is a promising design methodology that can significantly improve the performance of hybrid photovoltaic-thermal (PV-T) collectors. However, conventional spectral-splitting PVT (SSPVT) collectors require additional optical components, which significantly increases the complexity and cost of the collector. This study proposes SSPVT collector designs that employ semi-transparent photovoltaic (PV) solar cells, which act as both the electricity generator as well as the spectral-splitting optical filter. In these designs, a part of the solar spectrum is absorbed by the semi-transparent solar cells for electricity generation, while the rest (especially the near-infrared region of the solar spectrum) is transmitted to an absorber where it generates a high-temperature thermal energy output. Three types of emerging semi-transparent solar cells, i.e., cadmium telluride (CdTe), perovskite solar cells (PVSCs) and polymer solar cells (PSCs), are selected for investigation in this context. A comprehensive two-dimensional model of such SSPVT collectors is developed and used to investigate their electrical and thermal performance. The results show that the proposed designs are effective at thermally decoupling the PV cells from the solar thermal absorber, thereby promoting a higher electrical efficiency and enabling the simultaneous generation of low-temperature thermal energy (<60 °C), along with high-temperature thermal energy (100–200 °C) under one sun. For example, a PVSC-based SSPVT collector is shown to be capable of simultaneously generating: electricity with an efficiency of 13.8%, high-temperature heat (150 °C) with a thermal efficiency of 21.1%, and low-temperature heat (50 °C) with a thermal efficiency of 22.5%. The relative performance between the CdTe-, PVSC- and PSC-based collectors depend on the relative value of the high-temperature thermal energy to that of electricity. It is concluded that semi-transparent solar cells are of great promise in this application, and can give rise to next-generation, high-performance solar collectors.

Study of Capric-Palmitic Acid/Clay Minerals as Form-Stable Composite Phase-Change Materials for Thermal Energy Storage.

As an important method to effectively improve energy efficiency, the study of thermal energy storage is particularly important. In this study, six types of clay mineral-based form-stable phase-change materials (FSPCMs) were prepared by the vacuum adsorption method. The adsorption capacity of vermiculite and diatomite was satisfactory, and sepiolite showed the worst adsorption capacity. Clay minerals can delay the thermal decomposition rate of capric–palmitic acid (CA–PA), and the specific surface area and pore capacity of clay minerals all decrease dramatically after the clay minerals have absorbed CA–PA. FSPCMs exhibited a higher heat storage and release efficiency and reflects a certain temperature control performance. In addition, only physical adsorption between the CA–PA and the clay material occurred, and no chemical reaction occurred. Finally, FSPCMs still have high latent heat of phase transition, and they can be used for low-temperature thermal energy storage.

Thermo-economic analysis of working fluids for a ground source heat pump for domestic uses

Ground source heat pump, due to high coefficient of performance (COP) and use of low-temperature thermal energy source, is one of the best technologies to use renewable energy resources. In this work, at first, a geothermal heat pump for heating with an economizer is simulated, and then the effects of the variations in different parameters such as evaporator pressure, condensation pressure, and intermediate pressure on heat pump and total COP and exergy efficiency are analyzed. Initially, the thermodynamic simulation of the system is performed for different working fluids (R134a, R-12, R152a, R1234yf, and R1234ze(E)) in the EES software programming environment. The COP and exergy efficiency are calculated for different working fluids and obtained optimal values. The best overall coefficient of performance of the system is related to fluid R134a with a value of 3.663 and the best overall exergy efficiency of the system is related to fluid R1234ze(E) with a value of 0.5517. The lowest PCEU value is for fluid R152a with 0.01247$ per kilowatt. It can be concluded that by reducing the evaporator pressure of the cycle, the cost of producing an energy unit will be cheaper and by reducing the middle pressure of the cycle, the cost of producing an energy unit will be more expensive.

Thermal Stability and Reliability Test of Some Saturated Fatty Acids for Low and Medium Temperature Thermal Energy Storage

Phase change materials have been overwhelmingly used for thermal energy storage applications. Among organics, fatty acids are an important constituent of latent heat storage. Most of the saturated fatty acid PCMs so far studied are either unary or binary constituents of pure fatty acids. In the present study, ternary blends of saturated fatty acids i.e., capric, lauric, myristic, stearic, and palmitic acids have been developed with different weight proportions. A series of 28 ternary blends viz. CA-LA-MA, CA-LA-PA, CA-LA-SA, CA-MA-PA, CA-MA-SA, and CA-PA-SA were prepared and analyzed with differential scanning calorimetry, thermal gravimetric analysis, and Fourier transform infrared spectroscopy. DSC analysis revealed that the prepared materials lie in the 15–30 °C temperature range. Also, 300 thermal melt/freeze cycles were conducted which showed ±10% variation in terms of the melting peak for most of the PCMs, with the average latent heat of fusion between 130 and 170 kJ/kg. The TGA analysis showed that most of the PCMs are thermally stable up to 100 °C and useful for medium-low storage applications, and FTIR analysis showed that the materials are chemically stable after repeated thermal cycles. Based on cycle test performances, the developed materials were found to be reliable for long-term use in building and photovoltaic applications.

A Low-Temperature Phase Change Material Based on Capric-Stearic Acid/Expanded Graphite for Thermal Energy Storage.

In this study, a capric acid (CA)-stearic acid (SA)/expanded graphite (EG) composite phase change material (PCM) was prepared, and the optimum mass ratio of CA-SA is 0.84:0.16. The composite PCM was characterized by scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction. It can be concluded that the CA-SA mixture was found to possess good compatibility with EG, the thermal conductivity of the CA-SA/10 wt % EG composite PCM was 3.28 times higher than that of the CA-SA mixture, and the PCM thermal stability was satisfactory; no leakage occurred in the CA-SA/10 wt % EG composite PCM. The PCM has good thermal reliability after 500 thermal cycles. Finally, it is shown that the CA-SA/10 wt % EG composite PCM showed excellent performance, and therefore, it can be used for low-temperature thermal energy storage.

Rational Design of Thermocells Driven by the Volume Phase Transition of Hydrogel Nanoparticles.

Thermocells are thermoelectrochemical conversion systems for harvesting low-temperature thermal energy. Liquid-state thermocells are particularly desirable because of low cost and their high conversion efficiency at temperatures around physiological temperature, and they have, thus, been extensively studied. However, the performance of the thermocells has to be improved to utilize them as energy chargers and/or batteries. Recently, we reported that a liquid-state thermocell driven by the volume phase transition of hydrogel nanoparticles showed highly efficient thermoelectric conversion with Seebeck coefficient (Se) of -6.7 mV K-1. Here, we report the design rationale of the thermocells driven by the phase transition. A high Se of -9.5 mV K-1 was achieved at temperature between 36 and 40 °C by optimizing choice and amount of redox chemical species. The figure of merit (ZT) of the thermocell was improved by selecting appropriate electrolyte salt to increase the ionic conductivity and prevent the precipitation of nanoparticles. Furthermore, screening of nanoparticles revealed the high correlation between Se and the pH shift generated as a result of phase transition of the nanoparticles. After optimization, the maximum ZT of 8.0 × 10-2 was achieved at a temperature between 20 and 70 °C.

Anaerobic Corrosion of Zero-Valent Iron at Elevated Temperatures.

Increasing groundwater temperatures caused by global warming, subsurface infrastructure, or heat storage projects may interfere with groundwater remediation techniques using zero-valent iron (ZVI) technology by accelerating anaerobic corrosion. The corrosion behavior of three ZVIs widely used in permeable reactive barriers (PRBs), Peerless cast iron (PL), Gotthart-Maier cast iron (GM), and an ISPAT iron sponge (IS), was investigated at temperatures between 25 and 70 °C in half-open batch reactors by measuring the volume of hydrogen gas generated. Initially, the corrosion rates of all tested ZVIs increased with temperature; at temperatures ≤40 °C, a material-specific steady state is reached, and at temperatures >40 °C, passivation causes a decrease in long-term corrosion rates. The observed corrosion behavior was therefore assumed to be superimposed by accelerating and inhibiting effects, caused by surface precipitates where the fitting of measured corrosion rates by a modeling approach, using the corroded amount of Fe0 to account for passivating minerals, yields intrinsic activation energies (Ea, ZVI) of 81, 90, and 107 kJ mol-1 for IS, GM, and PL, respectively. An increase in H2 production might not be directly transferable to an increase in general ZVI reactivity; however, the results suggest that an increase in chlorinated hydrocarbon degradation rates can be expected for ZVI-PRBs in the immediate vicinity of low-temperature underground thermal energy storages (UTESs) or in the impact areas of high-temperature UTES with temperatures of ≤40 °C.

Effectiveness of Thermal Properties in Thermal Energy Storage Modeling

This paper studies the influence of material thermal properties on the charging dynamics in a low temperature Thermal Energy Storage, which combines sensible and latent heat. The analysis is based on a small scale packed bed with encapsulated PCMs, numerically solved using COMSOL Multiphysics. The PCMs studied are materials constructed based on typical thermal properties (melting temperature, density, specific heat capacity (solid and liquid), thermal conductivity (solid and liquid) and the latent heat) of storage mediums in literature. The range of values are: 25–65°C for the melting temperature, 10–500 kJ/kg for the latent heat, 600–1,000 kg/m3 for the density, 0.1–0.4 W/mK (solid and liquid) for the thermal conductivity and 1,000–2,200 J/kgK (solid and liquid) for the specific heat capacity. The temperature change is monitored at three different positions along the tank. The system consists of a 2D tank with L/D ratio of 1 at a starting temperature of 20°C. Water, as the heat transfer fluid, enters the tank at 90°C. Results indicate that latent heat is a leading parameter in the performance of the system, and that the thermal properties of the PCM in liquid phase influence the overall heat absorption more than its solid counterpart.

Multicomponent bio-based fatty acids system as phase change material for low temperature energy storage

In this study, new multicomponent mixtures of fatty acids for low temperature thermal energy storage applications have been developed. The new mixtures were based on coconut oil fatty acids (CoFA) and commercial grades of oleic (OA) and linoleic acid (LA). Refined coconut oil (CO) was first converted into free fatty acids by alkaline saponification. The prepared CoFA were then mixed with OA or LA at various compositions to prepare stable bio-based phase change materials (BPCMs). The thermal behavior including melting/solidification temperatures, specific heat and enthalpy of the developed mixtures were investigated by means of differential scanning calorimetry (DSC) and T-history. Transient hot wire method was used to measure thermal conductivity of the PCMs. The chemical stability and thermal reliability of the mixtures were assessed stepwise from 100 to 700 melt/freeze cycles by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and DSC. Based on DSC and T-history results, the phase transition of the developed PCMs were in line with the range of human comfort temperatures i.e. 18-25 °C, with no incongruent melting and less than 0.6 °C super cooling, whereas specific heat and enthalpy of the new mixtures were in the range of 1-5 J/g K, and 40-100 J/g. The FTIR and DSC results indicated that the PCMs mixtures are chemically and thermally stable. The thermal conductivity of the mixtures were in average 0.2 W/m K, in liquid phase and 0.35 W/m K, in solid phase. Out of the different developed combinations, the mixture of LA/CoFA (20/80) showed distinguished performance and can be considered as potential BPCM for low temperature thermal energy storage applications.

Performance optimization of an integrated adsorption-absorption cooling system driven by low-grade thermal energy

• Thermal characteristics of integrated absorption - adsorption systems were studied. • Optimal intermediate pressure and LiBr solution concentration were investigated. • Effect of heating and cooling flow arrangement on system performance was evaluated. • The integrated system produced a greater cooling capacity with a reliable high COP. • The AB-bottom-AD-top system performed better than the AD-bottom-AB-top system. The integrated adsorption-absorption system is a novel technology to convert low-temperature waste thermal energy into useful cooling, which substantially improves energy utilization efficiency and lowers environmental pollution. This novel system incorporates the adsorption cycle into the absorption cycle so that the generation/adsorption pressure can be adjusted to enhance the system performance at low-temperature heat sources. In this paper, the thermal characteristics of the integrated system are theoretically evaluated. The optimization of the key parameters (e.g. cycle time, switching time, intermediate pressure and solution concentration) are conducted to achieve the best system performance. Furthermore, different configurations of the integrated system and the effect of the heating and cooling flow arrangements on the system performance are also investigated. The results showed that the coefficient of performance of the proposed system was as high as 0.4 at a heat source temperature of 50 °C. As the heat source temperature increased from 50 to 85 °C, an optimal intermediate (generation/adsorption) pressure varied gently from 2.36 to 2.16 kPa while the optimal solution concentration increased from 52.4 to 65% to achieve the best system coefficient of performance. The results also showed that the maximum specific cooling power is 193.7 W/kg when the heating and cooling water flow arrangement are both in parallel. In contrast, the lowest specific cooling power is 157.9 W/kg for both heating and cooling water flow arrangements in series. When compared the two different configurations, the cooling capacity and coefficient of performance of the configuration with absorption-cycle as the bottom cycle and adsorption-cycle as the top cycle were about 5 and 15% higher, respectively than those of the configuration with adsorption-cycle as the bottom cycle and absorption-cycle as the top cycle.