Adsorption Refrigeration Cycle Research Articles

The Impact of Solar Radiation at Different Colombian Thermal Floors on an Adsorption Refrigeration Cycle

The process of energy transition in Colombia has sparked an exploration into appropriate geographical areas for the utilization of solar energy. The country’s rugged terrain and significant climate variability pose challenges for implementing standardized technologies uniformly across all regions. Consequently, this study aims to develop and apply a mathematical model to characterize the performance of a solar adsorption cooling system under the environmental conditions found in six distinct Colombian cities, taking into account different thermal profiles and extreme weather periods such as the El Niño and La Niña phenomena. The selected mathematical model was simulated in these cities, considering ambient temperature and solar radiation variables over a twelve-month period during these extreme weather phenomena and an additional twelve-month period representative of a typical year with minimal influence from these phenomena. The results indicated that despite a lower coefficient of performance (COP) compared to the other cities, Riohacha demonstrated a greater number of ice production days owing to its high levels of solar radiation.

Study of Dynamic Sorption in Adsorption Refrigeration Cycle

This paper shows the characteristics of temperature and adsorbed (water vapor) mass rate distribution in the adsorber unit which is the key part to any adsorption refrigeration system. The temperature profiles of adsorption/desorption phases (Dynamic Sorption) are measured experimentally under the operating conditions of 90oC hot water temperature, 30oC cooling water temperature, 35oC adsorption temperature and cycle time of 40 min. Based on the temperature profiles, The mass transfer equations for the annulus adsorbent bed are solved to obtain the distribution of adsorption velocity and adsorbate concentration using non-equilibriummodel. The relation between the adsorption velocity with time is investigated during the process of adsorption. The practical cycles of adsorption and desorption were stated dependent on the variables obtained from the experiment and equations calculations.The results show that the adsorption velocity is diminished after a period of 20 min. The maximum value of the adsorbed water vapor concentration on silica gel is 0.12 kg water/kg adsorbent (adsorption phase) and the minimum value of the water content into silica gel is 0.04 kg water/kg adsorbent (desorption phase) producing a dynamic sorption of kg water/kg adsorbent.

Modeling and optimizing a two-bed adsorption cooling system with a modified mass recovery process

A two-bed adsorption refrigeration cycle (ARC) with a new proposed modified mass recovery process is investigated (modeled, optimized and compared with ARC cycle with conventional mass recovery process) here. This proposed modified mass recovery process increases the system cooling capacity and cycle exergy efficiency. These achievements reached by opening the connecting valve between two beds during mass recovery process as usual, but continuing cooling of adsorption bed by water even during mass recovery process. Thus, the refrigerant vapor moved from desorber to adsorber bed in this situation by two effects, the higher pressure of refrigerant vapor in desorber bed and also due to higher effect of adsorption process for cooling of this bed by water. Furthermore, at the end of the proposed modified mass recovery process, the equilibrium pressure of beds was closer to the evaporator pressure than that for ARC with conventional mass recovery process. Thus, the new switched adsorption bed could connect to evaporator even during pre-cooling process. This makes connecting time period of evaporator and adsorber longer than that for ARC with the conventional mass recovery process. The above effects increased the amount of refrigerant vapor adsorbed in the adsorption bed which increased ARC cooling capacity as well. Finally to study the effects of various design variables, a two bed ARC with the proposed modified mass recovery cycle is modeled and optimized for a specific cooling capacity by considering coefficient of performance and exergy destruction as two objective functions. Results for a system with 14 kW (4 refrigeration tons) cooling capacity showed 0.555, 0.284 and 1719.6 kJ for optimum values of coefficient of performance (COP, with 0.9% increase), exergy efficiency (14% increase) and total exergy destruction (16.2% decrease), respectively in comparison with those for ARC with the conventional mass recovery process.

Effect of Adsorbent on the Performance of Double Effect Adsorption Refrigeration Cycle with Adsorption Heat Recovery

This study investigates the performance of double effect adsorption refrigeration cycle that utilizes the adsorption heat of a high-temperature adsorbent heat exchanger for desorption of a low-temperature one. Because there is a freedom to select an adsorbent for each adsorbent heat exchanger, the combination of adsorbents such as silica gel, FAM-Z01, FAM-Z02 and FAM-Z05 were examined. The temperature of an external heat source was assumed to be 90°C. Dynamic cycle simulation was employed to estimate the performance in terms of coefficient of performance (COP) and specific cooling power (SCP). The results show that the combination of the adsorbents FAM-Z01 and FAM-Z02 for the low-temperature heat exchanger and high-temperature one, respectively, is the most effective to achieve high COP as well as high SCP. The results also indicate that the COP=1.0 is attainable when the mass allocation of the adsorbents and the cycle time are selected appropriately. From the viewpoint of maximizing the cooling power, COP=0.9 is suggested for the best design, where the mass of high-temperature side is equal to the mass of low-temperature side.

Improving the Engine Efficiency Using a New Combined Refrigeration Cycle for Low-Temperature Heat Source (Waste Heat Recovery)

Passenger and commercial internal combustion engines have relatively large dissipated thermal energy sources that can be used for initiating thermodynamic refrigeration cycles at low temperatures while improving engine efficiency. Researchers have focused on combined power-refrigeration cycles in past studies. This paper presents the operation and performance of a new combined refrigeration system driven by waste heat recovery within the internal combustion engines. For this purpose, the effects of several parameters on the performance of the cycle are examined. Results show that an increase in the engine water temperature, exhaust gas temperature, part-load ratio (PLR), generator temperature, as well as adsorption evaporator temperature had a positive effect on the performance of the cycle. However, the rise in condenser temperature of the adsorption cooling system leads to bad performance. Also, the results indicate that the application of the adsorption refrigeration cycle in the combined cooling cycle, along with the increase in the refrigeration cycle performance by up to 65%, also improves the efficiency of the internal combustion engine.

Photovoltaic and Photovoltaic Thermal Technologies for Refrigeration Purposes: An Overview.

Refrigeration systems have a broad range of applications, playing a critical role in human life. Especially, vaccine preservation in rural regions has become more critical than in the past during the COVID19 era. In this sense, meeting the cooling process's energy need with renewable energy is critical, as the grid cannot support it. Thus, solar energy has been extensively studied for use in refrigeration cycles. Compression, absorption, adsorption, desiccant, and ejector refrigeration cycles are frequently used in this configuration. This article discusses multiple studies showing various attributes' impact on a system's overall efficiency. Most previous reviews did not cover PV with refrigeration cycles. So, this paper surveys the literature on PV-powered cooling cycles. For better classification, PV technologies are categorized into three types: PV, PVT, and CPVT. With this regard, CPVTs still have a way to progress due to a lack of studies compared to PV. The works are divided into three main sections as Exergy Studies, Experimental Studies, and Simulation and Numerical Studies. This review paper categorizes and rates refrigeration-assisted solar systems based on exergy destruction, exergy efficiency, and COP of cooling cycles. The results showed that PV panels have the highest exergy destruction in most of the systems. It is concluded that using PV technologies has a great potential to supply cooling demand, especially in a hot climate condition. Moreover, the study's findings are anticipated to aid designers in scaling up photovoltaic-based cooling systems, resulting in more efficient and sustainable designs.

Experimental investigation of optimal operation time for a double effect adsorption refrigeration cycle

Experimental investigation of optimal operation time for a double effect adsorption refrigeration cycle

Performance study of adsorption refrigeration system with composite adsorbent

As an effective way to improve the performance of heat and mass transfer, Composite adsorbent used in adsorption refrigeration has attracted increasing research attention. The aim of the research is to reveal composite theory of silica gel composite adsorbent and to understand adsorption refrigeration system mechanism running by above composite adsorbent. Coarse porous silica gel with different particle diameters was selected as the matrix of composite adsorbent and calcium chloride was selected as additive. The results showed that composite adsorbent's thermal conductivity and adsorption capacity increased significantly compared with pure silica gel. The thermal conductivity could be increased by 58.2%, and the adsorption capacity could be increased by 4–10 times. Finally, the adsorption refrigeration system using silica gel-calcium chloride composite adsorbent was studied. A two-bed adsorption refrigeration cycle running by above composite adsorbent was adopted. The experimental results showed that the optimal values of system cooling capacity and COP were not at the same time. The system cooling capacity reached its maximum at 1500 s and the system COP reached its maximum at 1200 s. The best heat recovery time was 20 s. The SCP of the system was up to 288.1 W kg−1, which could reduce the volume of the adsorption refrigeration system effectively.

Investigation The performance of a Linear Fresnel Solar Concentrator Integrated with an Adsorption Refrigeration Cycle

A large amount of the energy produced is used for heating and cooling application. Many studies at the present time are looking for ways to reduce this consumption or use a renewable energy source to reduce dependence on fossil fuel energy. In this research, the used of solar energy to power a hybrid adsorption ice-maker, a linear Fresnel solar concentrator type, with a total area of 5 m2, is used for this purpose The concentrator was designed, built and conducting an experimental study in Baghdad (latitude 33.33 and longitude 44.14) for the solar system that which is consisting of the concentrator with a double absorber type evacuated tube has been used, tank, pump and accessories to investigate the performance of the system and the effect of the water flow on the unit performance. The performance of the adsorption system is studied theoretically. The adsorption system works with the activated carbonmethanol pair the mass of activated carbon is 0.5 and while the mass of methanol is 1.6 kg. The experimental work was achieved at July 2019 and the results showed that the maximum temperature of the water inside the tank obtained was 95 °C when the rate of water flow through the collector loop was 0.5 kg/min and that the maximum thermal efficiency was about 40% at the same flow amount. The theoretical results showed that the best coefficient of performance for the adsorption refrigeration system was 0.43 at the generator temperature of 95 °C and the condensing temperature of 30 °C.

Experimental investigation of double effect adsorption refrigeration cycle with adsorption heat recovery

This research is aiming to demonstrate the operation of adsorption refrigeration cycle with adsorption heat recovery, and to research optimal operating conditions. Adsorption refrigerator is a kind of equipment that uses low-temperature heat to product cold heat, and it’s expected to be useful for more effective use of low-temperature waste heat. In previous research, the COP, which indicates efficiency of a refrigerator, of adsorption refrigerator with adsorption heat recovery was predicted to be 1.5 times higher than that of absorption refrigerator using same temperature range of waste heat by dynamic analysis. After that, the experimental device of adsorption refrigerator with adsorption heat recovery was manufactured, however, the cooling capacity was not confirmed. Therefore, in this research, because of some modifications, the cooling capacity was confirmed, and the COP was also found to be improved than adsorption refrigerator without adsorption heat recovery.

Recent progress and outlook of solar adsorption refrigeration systems

Solar adsorption refrigeration systems are indispensable in the areas of cooling such as air conditioning, ice making, food preservation, medicine and vaccine storage etc in remote areas. It is cheaper than other devices and lack in noise and corrosion. It is completely an eco-friendly system which could be driven by low grade waste heat. Consumption of electricity is very less in this system as compared to other fields due to the elimination of compression process in adsorption refrigeration. Most of the adsorption system delivers a COP between 0.1 and 0.2 and exceptions are also there. Because of the technical, economic and environmental problems, researches are going on in these areas. Nowadays it is incorporated with vapour compression system to make hybrid system in order to achieve a greater COP and efficiency. This paper presents the basic and advanced aspects of adsorption refrigeration cycle and its hybrid arrangements with pre-existing system. This paper described the different types of conventional and novel adsorbent – adsorbate working pairs and provides detailed review about the past and present state of art research in this field.

Energy saving research of natural gas liquefaction plant based on waste heat utilization of gas turbine exhaust

In this study, a series of novel natural gas liquefaction systems integrated with waste heat utilization of gas turbine exhaust are proposed to reduce the energy consumption of the liquefaction plants. The most widely used propane precooled mixed refrigerant (C3MR) and cascade natural gas liquefaction processes, are integrated with the waste heat utilization methods of adsorption refrigeration and organic Rankle cycle (ORC). The integrated systems are simulated and optimized with HYSYS software and genetic algorithm. The results show that, with ammonia water absorption refrigeration, the power consumption of C3MR process and cascade process is reduced by 16.23% and 14.62%, respectively, and the waste heat utilization exergy efficiency of the two integrated processes reaches 56.96% and 48.73%, respectively; With ORC, the power consumption is reduced by 20.59%, and the waste heat utilization exergy efficiency reaches 75.61%. In addition, for a liquefaction plant with an annual processing capacity of about 1.4 million tons, the waste heat utilization achieves CO2 emission reduction of about 4000–6000 t/a.

Simultaneous production of cooling and freshwater by an integrated indirect evaporative cooling and humidification-dehumidification desalination cycle

Cooling and freshwater represent two fundamental demands in hot and arid regions. This paper reports the integration of an indirect evaporative cooler (IEC) and a humidification-dehumidification desalination cycle (HDH) for the simultaneous production of cooling and freshwater. To take full advantage of system integration, the purge air from IEC is supplied to HDH to promote water productivity. A pilot IEC unit is firstly designed and tested to achieve the temperatures and humidity of the outlet air steams. Results reveal that the IEC unit is able to cool down the supply air to below 25 °C under different outdoor conditions, and the purge air temperature is also 5–10 ℃ lower than the intake air temperature. Employing the IEC purge air as the working air, the HDH cycle is then investigated analytically. Under the operation ranges considered, the freshwater productivity and gain-output ratio (GOR) are 25–125 L/hr and 1.6–2.5, respectively, which are higher than other HDH configurations operating under the same conditions. Finally, the performance of the combined IEC-HDH system is evaluated. The overall coefficient of performance (COP) and Second-law efficiency are found to be 2.1–2.5 and 3–26%, respectively. Further improvement of efficiency can be achieved by integrating with adsorption or vapor compression refrigeration cycles.

Performance comparative study of a solar-powered adsorption refrigerator with a CPC collector/adsorbent bed

Solar adsorption refrigeration has many advantages. However, solar radiation has a relatively low energy density and requires much time to heat an adsorbent bed. In addition, the coefficient of performance (COP) of an adsorption refrigeration system is relatively low. In this paper, a new solar adsorption refrigeration prototype, which uses a compound parabolic concentrator (CPC) adsorbent bed with activated carbon-methanol as the working pair, was proposed and built to shorten the cycle time and improve performance. Laboratory experiments were conducted to evaluate and compare its performance and characteristics to those of a conventional solar adsorption refrigeration system. The experimental results show that the speed of the temperature increase of the adsorbent bed was boosted by employing CPC collectors. Compared with a conventional refrigeration system, the desorption period of the new system was reduced by one-third over one cycle. The desorption rate of the adsorption refrigeration cycle was notably improved. By using the CPC collector in a solar adsorption refrigeration system, the COP increased by 27%. The experimental results also show that applying solar concentrating technology in adsorption refrigeration is a promising approach for improving solar adsorption refrigeration performance and achieving a fast and continuous refrigeration cycle.

Experimental study of the effect of enhanced mass transfer on the performance improvement of a solar-driven adsorption refrigeration system

The current work demonstrates a novel prototype of a solar adsorption refrigeration system with enhanced mass transfer based on an ideal basic solid adsorption refrigeration cycle with activated carbon-methanol as the working pair. The working principle of the hypothesis was analysed, and the coefficient of performance (COP) was used to assess the system’s performance. A solar simulator consisting of a halogen lamp light resource array was adopted to provide a light source for heating. Different comparative tests under different input radiation energy conditions were carried out to prove the hypothesis that a lower condensing pressure can be realized by using an enhanced mass transfer method and is good for increasing the amount of desorption. The variations of the adsorbent bed temperature, system pressure and ice production were analysed. The maximum COP and maximum ice-making capacity of the enhanced mass transfer adsorption refrigeration system were 0.142 and 7 kg, respectively. The average COP of the novel system showed an improvement of 35.9% compared with the average COP of the natural mass transfer adsorption refrigeration system when the input radiation energy was not less than 14.7 MJ during a refrigeration cycle.

Transient numerical model for predicting operating temperatures of solar adsorption refrigeration cycle

In this study, a transient numerical model, referred as CBSR model, was developed for determining the operating temperatures and its corresponding times of the solar adsorption refrigeration cycle with activated carbon AC35-methanol pair for unsteady solar irradiation. The operating temperatures and its corresponding times obtained by the present model compared with those of the literature showed an acceptable difference, whereas the study introduced most factors which can affect the performance of the machine. The presenting of the operating temperatures of the solar adsorption refrigeration cycle as a function of solar cold generation energy allowed to sweep the interval of cycle temperatures of functioning of the machine according to climatic conditions (solar irradiation and ambient temperature) and the required cold production. Accordingly, to achieve an optimum performance, the operating conditions can be notified in the user manual of the manufactured solar adsorption refrigerator.

A Preliminary Study on Designing and Testing of an Absorption Refrigeration Cycle Powered by Exhaust Gas of Combustion Engine

In order to recover the waste heat from the exhaust gas of a combustion engine, an adsorption refrigeration cycle is proposed. This is a preliminary study on design and testing of a prototype of absorption refrigeration cycle powered by an internal combustion engine. The heat source of the cycle is a compression ignition engine which generates 122.36 W of heat in generator of the cycle. The pairs of absorbent and refrigerant are water and ammonia. Here the generator is made of a shell and tube heat exchanger with number of tube and its length are 20 and 0.69 m, respectively. In the experiments the exhaust gas, with a mass flow rate of 0.00016 kg/s, enters the generator at 110°C and leaves it at 72°C. Here, the solution is heated from 30°C to 90°C. In the evaporator, the lowest temperature can be reached is 17.9°C and COP of the system is 0.45. The main conclusion can be drawn here is that the proposed system can be used to recycle the waste heat and produced cooling. However, the COP is still low.

Static analysis of triple-effect adsorption refrigeration with compressor

In order to improve the efficiency of the adsorption refrigeration cycle, this study proposes a triple-effect adsorption refrigeration cycle equipped with a compressor. This cycle can run in order to create a large variation in adsorbent concentration range by the compressor, even if there is little temperature variation in the desorption and adsorption processes. The objective of this study is to clarify the effect that regulating adsorption pressure using a compressor has on the adsorption refrigeration cycle, and to that end cycle efficiency was calculated using a static analysis based on a state of equilibrium. As a results from the simulation, the triple-effect cycles can operate by regulating adsorption pressure. Both COP and exergy efficiency can be improved by a factor of 1.2 if the cycled is regulated the adsorption pressure of each cycle rather than using a shared adsorption pressure. For heat sources in the temperature range of 70–100°C, this method is superior in terms of COP and exergy efficiency. COP values of approximately 1.7–1.8 can be obtained, which is three times higher than single-effect cycles. The triple-effect cycles have one-third the SCE of single-effect cycles but about the same SCE as double-effect cycles.

三重効用吸着冷凍サイクルの静的解析による性能評価

三重効用吸着冷凍サイクルの静的解析による性能評価

Temperature–heat diagram analysis method for heat recovery physical adsorption refrigeration cycle – Taking multi-stage cycle as an example

The method of temperature–heat (T–Q) diagram analysis was proposed in this article. In T–Q diagram, the area between two process curves along the temperature axis represents the irreversibility degree of heat transfer, which has the same dimension with entransy dissipation. T–Q diagram can be used to optimize the heat exchange configuration and the heat exchanger network of adsorption refrigeration systems. The proposed T–Q diagram and traditional energy, exergy and entropy analyses were adopted to a multi-stage heat recovery adsorption refrigeration system. Results show that the optimal heat recovery schemes determined through T–Q diagram and cycle entropy production analyses are identical, while T–Q diagram is more intuitional since the analysis procedure is done graphically. T–Q diagram can also be applied to analyze experiment related results of process temperatures, and is capable of giving an estimation of the performance improvement for heat recovery cycle.