Revista Principia - Divulgação Científica e Tecnológica do IFPB, 2021
No presente trabalho foi realizada uma investigação experimental em um sistema de climatização de... more No presente trabalho foi realizada uma investigação experimental em um sistema de climatização dessecante com a intenção de conhecer os benefícios da inserção de um rotor entálpico em sua estrutura. Basicamente, foi realizada uma análise da energia térmica consumida para reativar o sólido adsorvente de um rotor dessecante e também a efetividade do processo de desumidificação inerente ao sistema. Para isso, foram montadas duas bancadas de testes, a primeira formada por apenas um rotor dessecante, a segunda por um rotor dessecante e um rotor entálpico. Os resultados desse trabalho serviram para orientar a concepção de um novo sistema de climatização híbrido e também para mostrar a importância da inserção dos rotores entálpicos nos sistemas de climatização dessecantes. A combinação do rotor entálpico com o rotor dessecante, ofereceu maior vantagem ao sistema de climatização tanto em relação à sua efetividade de desumidificação quanto a possibilidade de consumir menos energia no process...
Adsorption-journal of The International Adsorption Society, 2001
There have been performed experimental measurements of effective thermal conductivity of silica-g... more There have been performed experimental measurements of effective thermal conductivity of silica-gel for a stagnant cylindrical fixed bed under transient and steady state conditions in the presence of dry air at different pressures and for different amounts of adsorbed water. The Bauer-Schlünder and Kunii-Smith models have been used to identify the thermal solid conductivity of silica gel pellets from measurements
Numerical Heat Transfer, Part A: Applications, 2001
This work analyzes the effects of variable porosity on the heat transfer by natural convection, i... more This work analyzes the effects of variable porosity on the heat transfer by natural convection, in a cavity with isothermal vertical walls and adiabatic horizontal ones and a porous medium inside. The hydrodynamic field in the porous medium is modelled according to the general model obtained by Brinkman's and Forchheimer's terms. An exponential variation of the porosity near the walls was considered. The equations in terms of the real variables were numerically solved by the finite-volume method, with a staggered variables arrangement. The pressure-velocity coupling was treated with the PRIME algorithm. The simulations involved both Darcian (Da = 10 -7 ) and non-Darcian flows (Da = 10 -6 ). In each case, the modified Rayleigh range (Ra m = Ra 2 Da) was from 10 to 1,000, and from 100 to 5,000, respectively. For the numerical simulation we considered Pr = 1, Rk = 1, A = 1, and k X = 0.36. The results are shown through streamlines and isotherms and velocity and temperatures profiles. This shows that the generalized method with variable porosity means an increase in the average Nusselt number. For physical validation, some experimental sets were simulated in which glass was the porous medium, and water, alcohol, and transformer oil were used as the fluids. The simulated results indicate that the adopted model reduces the discrepancy in the experimental results obtained with water and alcohol. We proposed a correlation to evaluate the average Nusselt number as a function of six parameters: Rayleigh number, Prandtl number, the dimensionless particle diameter, thermal conductivity ratio between solid and fluid phase, porosity, and the aspect ratio of the cavity.
In the first part of this paper, we present a transient model of radial heat conduction in infini... more In the first part of this paper, we present a transient model of radial heat conduction in infinitely large media to model the hot-wire technique. Pulse and a Heaviside heat sources are investigated. The general instantaneous solution is generated using Green's functions ...
Resumo. O presente trabalho trata da modelagem matemática, simulação numérica e análise dos fenôm... more Resumo. O presente trabalho trata da modelagem matemática, simulação numérica e análise dos fenômenos de transferência de calor e massa em rotores dessecantes e rotores entálpicos empregados respectivamente na desumidificação do ar úmido e na recuperação de energia. O problema consiste de um rotor cilíndrico rotativo, tipo Honeycomb, impregnado de material dessecante, através do qual passam dois fluxos de ar contrários: um de processo (adsorção) e outro de regeneração (dessorção). Foi testado e validado um modelo matemático unidimensional, transiente, envolvendo as transferências de calor e massa na corrente fluida e na matriz porosa adsortiva, sendo composto de equações de conservação de massa e de energia, uma isoterma de adsorção e relações psicrométricas. Este sistema de equações foi discretizado via método dos volumes finitos, formulação totalmente implícita, com arranjo desencontrado. O procedimento numérico para solução utilizou a técnica iterativa de Gauss-Seidel com sub-relaxação, exceto na equação da energia no dessecante onde empregou-se o algoritmo de Thomas (TDMA). Os resultados obtidos são apresentados em forma de perfis de temperatura e umidade absoluta nas seções de adsorção e dessorção. Nos rotores entálpicos, observou-se que o modelo de equilíbrio instantâneo apresentou um bom ajuste sem grande custo computacional. Entretanto nos rotores dessecantes, registrou-se uma certa discrepância que pode estar associada à resistência de difusão de massa na matriz dessecante que foi desprezada nesse modelo.
Tubular adsorption reactors have been used in solar cooling systems since 1983. The original desi... more Tubular adsorption reactors have been used in solar cooling systems since 1983. The original design consisted in a metal screen tube concentrically inserted into a copper tube; granules of solid adsorbent are packed in the space between the two tubes. Two experimental setups were used to measure the degree of contribution provided by radial adsorbate flow through the metal screen on adsorption kinetics: the first setup was composed by a tube fully filled with adsorbent, resulting in mainly axial adsorbate flow, while the second one was composed by an external tube with an internal, coaxial metal mesh tube leading to free adsorbent flow lengthwise, resulting in predominant radial flow through the adsorbent bed. The adsorption working pair was constituted by silica gel and water. This particular pair is preferred for adsorption chillers due to its superior thermodynamic characteristics. Temperature and mass measurements were made along the adsorption process to compare the heat and ma...
The main purpose of this work is to perform a thermal analysis in an air conditioning duct to ver... more The main purpose of this work is to perform a thermal analysis in an air conditioning duct to verify the influence of the thermal properties of the insulating material on the minimum thermal insulation thickness necessary to avoid the condensation of water vapor present in the air. The mathematical formulation is based on Fourier’s law and the first law of thermodynamics. A response surface, a contour plot and a mathematical model for the analyzed response variable, were obtained from an experimental design. Results indicate that the reduction of thermal conductivity and increase of emissivity of the insulating material contribute to the reduction of the minimum thermal insulation thickness.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2021
Desiccant cooling systems are widely recognized as an alternative technology to vapor compression... more Desiccant cooling systems are widely recognized as an alternative technology to vapor compression cooling. Desiccant systems are attractive for air conditioning applications due to the possible use of low-grade heat and green refrigerants in their operation. In such systems, air dehumidification is achieved using bed compacted with desiccant materials such as silica gel, activated alumina, and zeolite. Desiccant systems, on the other hand, present a low coefficient of performance due to the poor heat and mass transfer in the adsorbent bed. A way to enhance the heat and mass transfer in desiccant systems can be accomplished by optimizing the adsorbent packing in the bed. This paper presents a numerical investigation of the dynamics of water vapor adsorption in silica gel bidisperse bed. The adsorbent bed is compacted with particles of two different sizes to reduce the voids between the adsorbent particles and hence increase the amount of desiccant and the adsorbed water mass in the bed. The effect of bidisperse packing in the air dehumidification capacity and adsorbed water mass is studied. The influence of the pressure drop applied on the adsorbent column and the inlet air conditions in the dehumidification process is also investigated. The numerical results showed that bidisperse packing increases the dehumidification capacity (improvement of 22.9%) and the amount of water adsorbed (improvement of 25%) in the bed compared to the case where monodisperse packing is applied to the system, contributing to the improvement in the performance of desiccant beds in air conditioning applications.
The importance of adsorption refrigeration and air conditioning technology is growing, as a respo... more The importance of adsorption refrigeration and air conditioning technology is growing, as a response to the demand for more sustainable, low-carbon intensity technologies. These versatile systems work with heat from flat-plate solar collectors or waste heat at temperatures as low as 65 • C. However, the market share of adsorption chillers is still a niche. Power density is one of the key factors to improve market penetration of such systems, allowing for smaller equipment at lower cost. Specific heat capacity is one of the determining factors of performance, affecting cycle dynamics and thermal performance, being related to the couple adsorbent-adsorbate. However, few experiments in the literature have considered real-size adsorptive beds and combined heat capacity of the adsorbed phase, as presented here. A scanning calorimetry technique is used to validate a representative mathematical model. The intensity of endothermal peaks is directly related to the ones related to the specific heat capacity of the adsorbed phase. The cp values for the range considered were lower than the cp values for the liquid phase but were closer to the liquid phase than to the vapor phase.
Abstract This paper presents a numerical investigation of the dynamics of adsorption of pure meth... more Abstract This paper presents a numerical investigation of the dynamics of adsorption of pure methane in a packed column with activated carbon in order to optimize the fast charge process in adsorbed natural gas vessels. The investigation utilizes two main models. A model for the column that is described by mass, momentum, and energy balances in conjunction with the ideal gas equation and the monodisperse model for the adsorbent. The resulting equations are discretized by the finite-volume method. Several main findings were revealed from this investigation. Firstly, numerical results show that the mass transfer in the adsorbent has a great impact on the gas speed during the adsorption process. Secondly, the adsorbed mass of the column increases by reducing the gas inlet temperature. Lastly, it was observed that the saturation time in the column is a function of the applied pressure drop. In this case, the saturation time in the column varied between 500 and 1000 s. This range is considered satisfactory for the fast filling process of the column.
Revista Principia - Divulgação Científica e Tecnológica do IFPB, 2016
Os rotores dessecantes são trocadores rotativos de calor e massa, tipo ar-ar, impregnados com mat... more Os rotores dessecantes são trocadores rotativos de calor e massa, tipo ar-ar, impregnados com material adsorvente, utilizados para desumidificação do ar úmido. Neste trabalho, é realizado um estudo teórico-experimental sobre o comportamento/desempenho de um rotor dessecante, usado para sistema de condicionamento de ar dessecante, funcionando sob as condições climáticas da cidade de João Pessoa. O problema consiste de um rotor cilíndrico rotativo, tipo Honeycomb, impregnado de material dessecante, através do qual passam dois fluxos de ar contrários: um de processo (adsorção) e outro de regeneração (dessorção). Foi testado e validado um modelo matemático unidimensional, transiente, envolvendo as transferências de calor e massa na corrente fluida e na matriz adsortiva, sendo composta por equações de conservação de massa e de energia, uma isoterma de adsorção e relações psicrométricas. Esse sistema de equações foi discretizado via método dos volumes finitos, formulação totalmente implícita, com arranjo desencontrado. O procedimento numérico para solução utilizou a técnica iterativa de Gauss-Seidel com sub-relaxação e o algoritmo de Thomas (TDMA). Os resultados indicam que o modelo matemático necessita de aprimoramento para representar com maior precisão os resultados experimentais, pois apresentaram erros relativos máximos de 10% para temperatura e 14 % para razão de umidade.
Revista Principia - Divulgação Científica e Tecnológica do IFPB, 2016
O resfriamento evaporativo pode ser uma alternativa para substituir o condicionamento de ar (sist... more O resfriamento evaporativo pode ser uma alternativa para substituir o condicionamento de ar (sistema de compressão de vapor) dependendo das condições climáticas e das características da carga térmica da edificação. A transferência de calor e massa entre o ar e a película de água nos equipamentos evaporativos foi analisada teoricamente. Um resfriador evaporativo direto e uma torre de resfriamento foram simulados via modelos de Merkel e de Poppe para determinar a temperatura e razão de umidade na saída de cada equipamento. As equações diferenciais ordinárias resultantes foram resolvidas analiticamente quando possível e numericamente através dos métodos de Euler e Runger Kutta. Para validar os modelos simulados, os resultados obtidos do resfriador evaporativo e da torre de resfriamento foram comparados com dados disponíveis na literatura. O modelo de Merkel com soluções analíticas e numéricas foram avaliados realizando ajuste linear e na sequência ajuste quadrático da curva de saturaçã...
Adsorption technology is a promising, low carbon intensity option for air conditioning and refrig... more Adsorption technology is a promising, low carbon intensity option for air conditioning and refrigeration. Adsorption kinetics is a key performance factor for such systems. This paper presents an adsorption kinetics and performance assessment of an experimental adsorption chiller with silica gel and water as working pair. The adsorbent bed heat exchanger is equipped with silica gel in loose grains fitted between finned tubes. Pressure, temperature and adsorbate flow measurements along the thermodynamic cycle are performed for two different options of adsorbent particle fraction sizes to compare the resulting dynamics and performance. COP is 0.53 and SCP is 68 WÁkg À1 for 2.0 mm dia. silica gel and a 80/30/15°C triplet. COP is 4 % worse when 0.26 mm silica gel is used, due to the lower porosity and lower thermal conductivity presented by the crushed adsorbent. A mass diffusion algorithm is considered in the numerical model. Good agreement between experimental and calculated data has been reached. The maximum temperature level needed for desorption in the 70-80°C range is compatible with the use of water heated by flat-type solar collectors, and low-grade waste heat from industrial processes.
Revista Principia - Divulgação Científica e Tecnológica do IFPB, 2021
No presente trabalho foi realizada uma investigação experimental em um sistema de climatização de... more No presente trabalho foi realizada uma investigação experimental em um sistema de climatização dessecante com a intenção de conhecer os benefícios da inserção de um rotor entálpico em sua estrutura. Basicamente, foi realizada uma análise da energia térmica consumida para reativar o sólido adsorvente de um rotor dessecante e também a efetividade do processo de desumidificação inerente ao sistema. Para isso, foram montadas duas bancadas de testes, a primeira formada por apenas um rotor dessecante, a segunda por um rotor dessecante e um rotor entálpico. Os resultados desse trabalho serviram para orientar a concepção de um novo sistema de climatização híbrido e também para mostrar a importância da inserção dos rotores entálpicos nos sistemas de climatização dessecantes. A combinação do rotor entálpico com o rotor dessecante, ofereceu maior vantagem ao sistema de climatização tanto em relação à sua efetividade de desumidificação quanto a possibilidade de consumir menos energia no process...
Adsorption-journal of The International Adsorption Society, 2001
There have been performed experimental measurements of effective thermal conductivity of silica-g... more There have been performed experimental measurements of effective thermal conductivity of silica-gel for a stagnant cylindrical fixed bed under transient and steady state conditions in the presence of dry air at different pressures and for different amounts of adsorbed water. The Bauer-Schlünder and Kunii-Smith models have been used to identify the thermal solid conductivity of silica gel pellets from measurements
Numerical Heat Transfer, Part A: Applications, 2001
This work analyzes the effects of variable porosity on the heat transfer by natural convection, i... more This work analyzes the effects of variable porosity on the heat transfer by natural convection, in a cavity with isothermal vertical walls and adiabatic horizontal ones and a porous medium inside. The hydrodynamic field in the porous medium is modelled according to the general model obtained by Brinkman's and Forchheimer's terms. An exponential variation of the porosity near the walls was considered. The equations in terms of the real variables were numerically solved by the finite-volume method, with a staggered variables arrangement. The pressure-velocity coupling was treated with the PRIME algorithm. The simulations involved both Darcian (Da = 10 -7 ) and non-Darcian flows (Da = 10 -6 ). In each case, the modified Rayleigh range (Ra m = Ra 2 Da) was from 10 to 1,000, and from 100 to 5,000, respectively. For the numerical simulation we considered Pr = 1, Rk = 1, A = 1, and k X = 0.36. The results are shown through streamlines and isotherms and velocity and temperatures profiles. This shows that the generalized method with variable porosity means an increase in the average Nusselt number. For physical validation, some experimental sets were simulated in which glass was the porous medium, and water, alcohol, and transformer oil were used as the fluids. The simulated results indicate that the adopted model reduces the discrepancy in the experimental results obtained with water and alcohol. We proposed a correlation to evaluate the average Nusselt number as a function of six parameters: Rayleigh number, Prandtl number, the dimensionless particle diameter, thermal conductivity ratio between solid and fluid phase, porosity, and the aspect ratio of the cavity.
In the first part of this paper, we present a transient model of radial heat conduction in infini... more In the first part of this paper, we present a transient model of radial heat conduction in infinitely large media to model the hot-wire technique. Pulse and a Heaviside heat sources are investigated. The general instantaneous solution is generated using Green's functions ...
Resumo. O presente trabalho trata da modelagem matemática, simulação numérica e análise dos fenôm... more Resumo. O presente trabalho trata da modelagem matemática, simulação numérica e análise dos fenômenos de transferência de calor e massa em rotores dessecantes e rotores entálpicos empregados respectivamente na desumidificação do ar úmido e na recuperação de energia. O problema consiste de um rotor cilíndrico rotativo, tipo Honeycomb, impregnado de material dessecante, através do qual passam dois fluxos de ar contrários: um de processo (adsorção) e outro de regeneração (dessorção). Foi testado e validado um modelo matemático unidimensional, transiente, envolvendo as transferências de calor e massa na corrente fluida e na matriz porosa adsortiva, sendo composto de equações de conservação de massa e de energia, uma isoterma de adsorção e relações psicrométricas. Este sistema de equações foi discretizado via método dos volumes finitos, formulação totalmente implícita, com arranjo desencontrado. O procedimento numérico para solução utilizou a técnica iterativa de Gauss-Seidel com sub-relaxação, exceto na equação da energia no dessecante onde empregou-se o algoritmo de Thomas (TDMA). Os resultados obtidos são apresentados em forma de perfis de temperatura e umidade absoluta nas seções de adsorção e dessorção. Nos rotores entálpicos, observou-se que o modelo de equilíbrio instantâneo apresentou um bom ajuste sem grande custo computacional. Entretanto nos rotores dessecantes, registrou-se uma certa discrepância que pode estar associada à resistência de difusão de massa na matriz dessecante que foi desprezada nesse modelo.
Tubular adsorption reactors have been used in solar cooling systems since 1983. The original desi... more Tubular adsorption reactors have been used in solar cooling systems since 1983. The original design consisted in a metal screen tube concentrically inserted into a copper tube; granules of solid adsorbent are packed in the space between the two tubes. Two experimental setups were used to measure the degree of contribution provided by radial adsorbate flow through the metal screen on adsorption kinetics: the first setup was composed by a tube fully filled with adsorbent, resulting in mainly axial adsorbate flow, while the second one was composed by an external tube with an internal, coaxial metal mesh tube leading to free adsorbent flow lengthwise, resulting in predominant radial flow through the adsorbent bed. The adsorption working pair was constituted by silica gel and water. This particular pair is preferred for adsorption chillers due to its superior thermodynamic characteristics. Temperature and mass measurements were made along the adsorption process to compare the heat and ma...
The main purpose of this work is to perform a thermal analysis in an air conditioning duct to ver... more The main purpose of this work is to perform a thermal analysis in an air conditioning duct to verify the influence of the thermal properties of the insulating material on the minimum thermal insulation thickness necessary to avoid the condensation of water vapor present in the air. The mathematical formulation is based on Fourier’s law and the first law of thermodynamics. A response surface, a contour plot and a mathematical model for the analyzed response variable, were obtained from an experimental design. Results indicate that the reduction of thermal conductivity and increase of emissivity of the insulating material contribute to the reduction of the minimum thermal insulation thickness.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2021
Desiccant cooling systems are widely recognized as an alternative technology to vapor compression... more Desiccant cooling systems are widely recognized as an alternative technology to vapor compression cooling. Desiccant systems are attractive for air conditioning applications due to the possible use of low-grade heat and green refrigerants in their operation. In such systems, air dehumidification is achieved using bed compacted with desiccant materials such as silica gel, activated alumina, and zeolite. Desiccant systems, on the other hand, present a low coefficient of performance due to the poor heat and mass transfer in the adsorbent bed. A way to enhance the heat and mass transfer in desiccant systems can be accomplished by optimizing the adsorbent packing in the bed. This paper presents a numerical investigation of the dynamics of water vapor adsorption in silica gel bidisperse bed. The adsorbent bed is compacted with particles of two different sizes to reduce the voids between the adsorbent particles and hence increase the amount of desiccant and the adsorbed water mass in the bed. The effect of bidisperse packing in the air dehumidification capacity and adsorbed water mass is studied. The influence of the pressure drop applied on the adsorbent column and the inlet air conditions in the dehumidification process is also investigated. The numerical results showed that bidisperse packing increases the dehumidification capacity (improvement of 22.9%) and the amount of water adsorbed (improvement of 25%) in the bed compared to the case where monodisperse packing is applied to the system, contributing to the improvement in the performance of desiccant beds in air conditioning applications.
The importance of adsorption refrigeration and air conditioning technology is growing, as a respo... more The importance of adsorption refrigeration and air conditioning technology is growing, as a response to the demand for more sustainable, low-carbon intensity technologies. These versatile systems work with heat from flat-plate solar collectors or waste heat at temperatures as low as 65 • C. However, the market share of adsorption chillers is still a niche. Power density is one of the key factors to improve market penetration of such systems, allowing for smaller equipment at lower cost. Specific heat capacity is one of the determining factors of performance, affecting cycle dynamics and thermal performance, being related to the couple adsorbent-adsorbate. However, few experiments in the literature have considered real-size adsorptive beds and combined heat capacity of the adsorbed phase, as presented here. A scanning calorimetry technique is used to validate a representative mathematical model. The intensity of endothermal peaks is directly related to the ones related to the specific heat capacity of the adsorbed phase. The cp values for the range considered were lower than the cp values for the liquid phase but were closer to the liquid phase than to the vapor phase.
Abstract This paper presents a numerical investigation of the dynamics of adsorption of pure meth... more Abstract This paper presents a numerical investigation of the dynamics of adsorption of pure methane in a packed column with activated carbon in order to optimize the fast charge process in adsorbed natural gas vessels. The investigation utilizes two main models. A model for the column that is described by mass, momentum, and energy balances in conjunction with the ideal gas equation and the monodisperse model for the adsorbent. The resulting equations are discretized by the finite-volume method. Several main findings were revealed from this investigation. Firstly, numerical results show that the mass transfer in the adsorbent has a great impact on the gas speed during the adsorption process. Secondly, the adsorbed mass of the column increases by reducing the gas inlet temperature. Lastly, it was observed that the saturation time in the column is a function of the applied pressure drop. In this case, the saturation time in the column varied between 500 and 1000 s. This range is considered satisfactory for the fast filling process of the column.
Revista Principia - Divulgação Científica e Tecnológica do IFPB, 2016
Os rotores dessecantes são trocadores rotativos de calor e massa, tipo ar-ar, impregnados com mat... more Os rotores dessecantes são trocadores rotativos de calor e massa, tipo ar-ar, impregnados com material adsorvente, utilizados para desumidificação do ar úmido. Neste trabalho, é realizado um estudo teórico-experimental sobre o comportamento/desempenho de um rotor dessecante, usado para sistema de condicionamento de ar dessecante, funcionando sob as condições climáticas da cidade de João Pessoa. O problema consiste de um rotor cilíndrico rotativo, tipo Honeycomb, impregnado de material dessecante, através do qual passam dois fluxos de ar contrários: um de processo (adsorção) e outro de regeneração (dessorção). Foi testado e validado um modelo matemático unidimensional, transiente, envolvendo as transferências de calor e massa na corrente fluida e na matriz adsortiva, sendo composta por equações de conservação de massa e de energia, uma isoterma de adsorção e relações psicrométricas. Esse sistema de equações foi discretizado via método dos volumes finitos, formulação totalmente implícita, com arranjo desencontrado. O procedimento numérico para solução utilizou a técnica iterativa de Gauss-Seidel com sub-relaxação e o algoritmo de Thomas (TDMA). Os resultados indicam que o modelo matemático necessita de aprimoramento para representar com maior precisão os resultados experimentais, pois apresentaram erros relativos máximos de 10% para temperatura e 14 % para razão de umidade.
Revista Principia - Divulgação Científica e Tecnológica do IFPB, 2016
O resfriamento evaporativo pode ser uma alternativa para substituir o condicionamento de ar (sist... more O resfriamento evaporativo pode ser uma alternativa para substituir o condicionamento de ar (sistema de compressão de vapor) dependendo das condições climáticas e das características da carga térmica da edificação. A transferência de calor e massa entre o ar e a película de água nos equipamentos evaporativos foi analisada teoricamente. Um resfriador evaporativo direto e uma torre de resfriamento foram simulados via modelos de Merkel e de Poppe para determinar a temperatura e razão de umidade na saída de cada equipamento. As equações diferenciais ordinárias resultantes foram resolvidas analiticamente quando possível e numericamente através dos métodos de Euler e Runger Kutta. Para validar os modelos simulados, os resultados obtidos do resfriador evaporativo e da torre de resfriamento foram comparados com dados disponíveis na literatura. O modelo de Merkel com soluções analíticas e numéricas foram avaliados realizando ajuste linear e na sequência ajuste quadrático da curva de saturaçã...
Adsorption technology is a promising, low carbon intensity option for air conditioning and refrig... more Adsorption technology is a promising, low carbon intensity option for air conditioning and refrigeration. Adsorption kinetics is a key performance factor for such systems. This paper presents an adsorption kinetics and performance assessment of an experimental adsorption chiller with silica gel and water as working pair. The adsorbent bed heat exchanger is equipped with silica gel in loose grains fitted between finned tubes. Pressure, temperature and adsorbate flow measurements along the thermodynamic cycle are performed for two different options of adsorbent particle fraction sizes to compare the resulting dynamics and performance. COP is 0.53 and SCP is 68 WÁkg À1 for 2.0 mm dia. silica gel and a 80/30/15°C triplet. COP is 4 % worse when 0.26 mm silica gel is used, due to the lower porosity and lower thermal conductivity presented by the crushed adsorbent. A mass diffusion algorithm is considered in the numerical model. Good agreement between experimental and calculated data has been reached. The maximum temperature level needed for desorption in the 70-80°C range is compatible with the use of water heated by flat-type solar collectors, and low-grade waste heat from industrial processes.
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Papers by José Gurgel