scholarly journals Preliminary Results on Experimental Modelling of an Adsorption Chiller

2021 ◽  
Vol 6 ◽  
pp. 29
Author(s):  
Nayrana Daborer-Prado ◽  
Alois Resch
Keyword(s):  
Numerical Model ◽  
Water Cycle ◽  
Cooling System ◽  
Numerical Study ◽  
Lumped Parameter Model ◽  
Coefficient Of Performance ◽  
Adsorption Refrigeration ◽  
Experimental Modelling ◽  
Adsorption Chiller ◽  
Lumped Parameter

Adsorption refrigeration, as a renewable cooling method, has received more attention in the last few years. The interest in this technology comes especially from developing and tropical countries, where the demand for cooling increases every year due to economy and population growth. Based on this scenario, this work aims to develop a numerical model of an adsorption chiller driven with solar energy, which can be used to optimize the cooling system operation of the building where the device is situated and compare it with the current cooling methods in use. The numerical study here presented was created using Matlab/Simulink™, it is based on a lumped parameter model that relies on physical properties and represents a cooling system using a pair of silica gel-water in a two-bed chiller. In this study, the authors proposed a simplified version of the system and the numerical model, which aims to reduce the simulation time and provide faster results. Besides the temperatures in the system, which range from 52 °C to 72 °C in the hot cycle and 12 °C to 23 °C in the chilled water cycle, the results also include the variation of water uptake in the two adsorbent beds. In general, the simulated temperature, cooling and heating power and coefficient of performance (COP) are in fair agreement with the literature data, nevertheless, the final results show that improvements still have to be performed.

Improvement of COP with Heat Recovery Scheme for Solar Adsorption Cooling System

2018 ◽  
Vol 26 (02) ◽  
pp. 1850016 ◽  
Author(s):  
K. M. Ariful Kabir ◽  
Rifat A. Rouf ◽  
M. M. A. Sarker ◽  
K. C. Amanul Alam ◽  
Bidyut B. Saha
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Cooling System ◽  
Continuous System ◽  
Recovery Process ◽  
Coefficient Of Performance ◽  
Heat Transfer Fluid ◽  
Adsorption Refrigeration ◽  
Adsorption Chiller ◽  
Adsorption Cooling System

Heat recovery ensures optimum usage of the collected energy, and thus, minimizes heat loss for a solar adsorption chiller. Two-bed adsorption chiller with conventional single stage, run by direct solar coupling with heat recovery, has been studied mathematically. In a heat recovery adsorption refrigeration system, to facilitate heat transfer, heat transfer fluid is distributed between two adsorbers maintaining the same mass flow rate. There is no mass transfer between system components during this phase. It is a semi-continuous system performed between two adsorption beds. After completion of desorption/condensation mode, heat transfer fluid is allowed to circulate between the heated desorber and the cooled adsorber. This process distributes some heat of the desorption bed to the adsorber preparing it for the next preheating mode where heat transfer between them is done adiabatically. Consequently, the performance has been checked and a satisfactory increase in the Coefficient of Performance (COP) (approximately 15%) has been detected in the calculated results for the heat recovery operation. It is also observed that the heat recovery process enhances the working hour and overall performances of the solar heat driven adsorption chiller.

A Fast and Effective Method for the Optimization of the Valve Plate of Swashplate Axial Piston Pumps

2021 ◽  
Author(s):  
Gianluca Marinaro ◽  
Emma Frosina ◽  
Kim Stelson ◽  
Adolfo Senatore
Keyword(s):  
Numerical Model ◽  
Dynamic Pressure ◽  
Valve Plate ◽  
Lumped Parameter Model ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Flow Ripple ◽  
Lumped Parameter ◽  
Pressure Ripple ◽  
Axial Piston

Abstract This research presents a lumped parameter numerical model aimed at designing and optimizing an axial piston pump. For the first time, it has been shown that a lumped parameter model can accurately model axial piston pump dynamics based on a comparison with CFD models and experimental results. Since the method is much more efficient than CFD, it can optimize the design. Both steady-state and dynamic behaviors have been analyzed. The model results have been compared with experimental data, showing a good capacity in predicting the pump performance, including pressure ripple. The swashplate dynamics have been investigated experimentally, measuring the dynamic pressure which controls the pump displacement; a comparison with the numerical model results confirmed the high accuracy. An optimization process has been conducted on the valve plate geometry to control fluid-born noise by flow ripple reduction. The NLPQL algorithm is used since it is suitable for this study. The objective function to minimize is the well-known function, the Non-Uniformity Grade, a parameter directly correlated with flow ripple. A prototype of the best design has been realized and tested, confirming a reduction in the pressure ripple. An endurance test was also conducted. As predicted from the numerical model, a significant reduction of cavitation erosion was observed.

Influence of Outside Temperature on the Operation of the Adsorption Chiller

2017 ◽  
Author(s):  
Andrzej Grzebielec ◽  
Rafał Laskowski ◽  
Adam Ruciński
Keyword(s):  
Waste Heat ◽  
Experimental Studies ◽  
Coefficient Of Performance ◽  
External Parameter ◽  
Adsorption Refrigeration ◽  
Adsorption Chiller ◽  
Type Device ◽  
Lower Temperature

Adsorption refrigeration systems are characterized by a lower coefficient of performance than the compressor type device or even absorption, but can utilize waste heat at lower temperature. The aim of the study was to determine which external parameter has the greatest impact on the efficiency of the adsorption device. As a result of experimental studies there was found that this is not the temperature of the feed but particularly the temperature of external air. For this reason, it is recommended that the adsorption device should cooperate with evaporative spray coolers, instead of with popular dry coolers. This solution will increase annual efficiency of adsorption unit approx. by 25% and significantly reduce the costs of cold generation.

scholarly journals Experimental and Theoretical Study of the Energy Flow of a Two Stages Four Generators Adsorption Chiller

2019 ◽  
Vol 14 (2) ◽  
pp. 129-136
Author(s):  
Faeza Mahdi Hadi
Keyword(s):  
Activated Carbon ◽  
Cold Water ◽  
Water Cycle ◽  
Electrical Power ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Low Grade ◽  
Adsorption Chiller ◽  
Two Stages

This work is concerned with a two stages four beds adsorption chiller utilizing activated carbon-methanol adsorption pair that operates on six separated processes. The four beds that act as thermal compressors are powered by a low grade thermal energy in the form of hot water at a temperature range of 65 to 83 °C.  As well as, the water pumps and control cycle consume insignificant electrical power. This adsorption chiller consists of three water cycles. The first water cycle is the driven hot water cycle. The second cycle is the cold water cycle to cool the carbon, which adsorbs the methanol. Finally, the chilled water cycle that is used to overcome the building load. The theoretical results showed that average cycle cooling power is 2.15kW, while the experimental measurement revealed that the cooling capacity of the cycle is about 1.98 kW with a relative error of % 0.02. The generator and condensing temperatures are 83 and 30 °C, respectively. The coefficient of performance (COP) of that chiller was in the range of 0.37 to 0.49. The best operating point and the best working conditions were also investigated. The present chiller is superior more than the single stage, two beds adsorption chiller that works on the activated carbon methanol pair that needs a high ambient temperature.

Two-Stage Non-Regenerative Silica Gel-Water Adsorption Refrigeration Cycle

2000 ◽  
Author(s):  
B. B. Saha ◽  
K. C. A. Alam ◽  
A. Akisawa ◽  
T. Kashiwagi ◽  
K. C. Ng ◽  
...  
Keyword(s):  
Heat Pump ◽  
Silica Gel ◽  
Water Adsorption ◽  
Waste Heat ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Adsorption Refrigeration ◽  
Two Stage ◽  
Adsorption Chiller ◽  
Adsorption Heat Pump

Abstract Over the past two decades there have been considerable efforts to use adsorption (solid/vapor) for cooling and heat pump applications, but intensified efforts were initiated only since the imposition of international restrictions on the production and use of CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons). Closed-type, conventional adsorption refrigeration and heat pump systems have an increasing market share in Japan. In this paper, a two-stage non-regenerative, silica gel-water adsorption chiller design is outlined. Experimental measurements are performed on a prototype of a 3.5 kW rated cooling capacity adsorption heat pump in order to determine its performance under different operating temperatures (hot, cooling and chilled water). The chiller performance is analyzed in terms of cooling capacity and coefficient of performance (COP). The main innovative feature in the two-stage adsorption chiller is the ability to utilize low-temperature waste heat (∼55°C) as the driving source with a cooling source of 30°C. The technological difficulty inherent in operating a thermally activated cycle with such a small regenerating temperature lift (temperature difference between heat source and heat sink inlets) is overcome by use of a two-stage cycle.

scholarly journals Study and Analysis by Numerical Simulation of a Solar Continuous Adsorption Chiller

2015 ◽  
Vol 773-774 ◽  
pp. 605-609
Author(s):  
Rabah Gomri ◽  
Billel Mebarki
Keyword(s):  
Solar Energy ◽  
Cooling System ◽  
Recovery Process ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Solar Collectors ◽  
Adsorption Refrigeration ◽  
Continuous Adsorption ◽  
Adsorption Cooling System ◽  
Mass Recovery

Environment and energy problems over the world have motivated researchers to develop energy systems more sustainable, having as one of the possible alternative the use of solar energy as source for cooling systems. Adsorption refrigeration systems are regarded as environmentally friendly alternatives to conventional vapour compression refrigeration systems, since they can use refrigerants that do not contribute to ozone layer depletion and global warming. In this paper a performance comparison between a solar continuous adsorption cooling system without mass recovery process and solar continuous adsorption cooling system with mass recovery process is carried out. Silica-Gel as adsorbent and water as refrigerant are selected. The results show that the adsorption refrigeration machine driven by solar energy can operate effectively during four months and is able to produce cold continuously along the 24 hours of the day. The importance of the mass recovery is proved in this study by increasing the coefficient of performance and the cooling capacity produced. For the same cooling capacity produced, the required number of solar collectors with mass recovery system is lower than the required number of solar collectors in the case of the refrigeration unit without mass recovery. For the same cooling capacity the system with mass recovery process allowed lower generation temperature.

A Consistent, Hybrid-Dynamical-System, Lumped-Parameter Model of Tire–Terrain Interactions

2015 ◽  
Vol 10 (3) ◽  
Author(s):  
Pravesh Sanghvi ◽  
Harry Dankowicz
Keyword(s):  
Dynamical System ◽  
Shear Failure ◽  
Internal State ◽  
Numerical Study ◽  
Lumped Parameter Model ◽  
State Variables ◽  
Hybrid Dynamical System ◽  
Steady State Condition ◽  
Internal State Variables ◽  
Lumped Parameter

This paper establishes the internal mathematical and energetic consistency of a hybrid-dynamical-system, lumped-parameter, planar, physical model for capturing transient interactions between an elastically deformable tire and an elastically deformable terrain as a baseline result for more realistic models that account for permanent deformation, shear failure, and three-dimensional contact conditions. The model accounts for radial and circumferential deformation of the tire as well as normal and tangential deformation of the terrain. It captures the onset and loss of contact as well as localized stick and slip phases for each of the discrete tire elements by a suitable evolution of a collection of associated internal state variables. The analysis characterizes generic transitions between distinct phases of contact uniquely in forward time and proves that all internal state variables remain bounded during compact intervals of contact. The behavior of the model is further illustrated through an analytical and numerical study of two instances of tire-terrain interactions under steady state condition.

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