Bidyut Baran Saha | Last modified date:2024.03.15 |
Professor /
Interdisciplinary Graduate School of Engineering Sciences, Advanced Graduate Program in Global Strategy for Green Asia
Multiscale Science and Engineering for Energy and the Environment Thrust
International Institute for Carbon-Neutral Energy Research
Multiscale Science and Engineering for Energy and the Environment Thrust
International Institute for Carbon-Neutral Energy Research
Graduate School
Administration Post
Other
Other
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Homepage
https://kyushu-u.elsevierpure.com/en/persons/bidyut-baran-saha
Reseacher Profiling Tool Kyushu University Pure
http://i2cner.kyushu-u.ac.jp/~saha/index.html
Phone
092-802-6722
Fax
092-583-8909
Academic Degree
Doctor of Engineering
Country of degree conferring institution (Overseas)
Yes Bachelor Master
Field of Specialization
Thermal Engineering, Heat Transfer, Refrigeration and Air-conditioning Engineering, Adsorption Desalination, Energy Efficiency Analysis
ORCID(Open Researcher and Contributor ID)
0000-0002-9902-2642
Total Priod of education and research career in the foreign country
03years02months
Outline Activities
1. Adsorption Sciences and Technology:
1.1 Adsorption Sciences
(i) A theoretical framework for the estimation of the isosteric heat of adsorption between an adsorbate (vapor) and an adsorbent (solid) is proposed based on the thermodynamic requirements of chemical equilibrium, Maxwell relations and the entropy of the adsorbed phase. The derived equation for the isosteric heat of adsorption is verified against three sets of judiciously selected adsorbent + adsorbate data that are found in the literature and the predictions are found to agree within the experimental uncertainties of the reported data.
(ii) A thermodynamic framework for calculating the specific heat capacity of a single component adsorbent + adsorbate system has been derived and developed using the classical thermodynamics, and these are essential for the design of adsorption processes. The derived formulation of the is compared with experimentally measured of adsorbent + adsorbate systems. The purpose of this letter is to fill up the information gap with respect to the state of adsorbed phase to dispel the confusion as to what is the actual state of the adsorbed phase.
(iii) We have developed the complete thermodynamic property fields for a single-component adsorbent + adsorbate system. These equations enable us to compute for the actual specific heat capacity, partial enthalpy and entropy which are essential for the analyses of single-component adsorption processes.
(iv) A considerable progress has been made for the development of novel porous materials with controlled architectures and surface treatment. An important feature of these adsorbent materials is the maximization of adsorption capacity at Henry’s region. A thermodynamic framework is presented to capture the relationship between the pore specific surface areas with the enthalpy of adsorption. Using this approach, the scientific community can be guided to the development of advanced porous adsorbent and adsorbate pairs. The adsorbents with the highest porous surface areas tend to possess lower isosteric heat of adsorption when storing the methane and hydrogen gases at room temperature.
1.1.1 Adsorption isotherms and kinetics
The adsorption characteristics of (i) pure water vapor on two different types of parent silica gels of type “RD” and “A” and Cu sputtered silica gel, (ii) n-butane, methane, R134a and R507A on functional activated carbon (Maxsorb III), and (iii) ethanol on activated carbon fiber (ACF) of types A-15 and A-20 at temperatures from 273 to 338 K and at different equilibrium pressures are experimentally studied by a volumetric technique and a thermo-gravimetric analyzer (TGA). The thermophysical properties such as skeletal density, BET surface area, pore size, pore volume and the total porosity of silica gel, Maxsorb III are determined.
We have measured experimentally the adsorption kinetics of (i) water on silica gel (type RD, cu-sputtered RD), (ii) ethanol and methanol on pitch-based activated carbon, activated carbon fibers, (iii) ethanol on to surface treated parent activated carbons and (iv) ethanol on Metal Organic Frameworks material namely MIL-101Cr, at different adsorption temperatures ranging from 27 to 70°C, which are suitable for adsorption chiller design. The ligand and metal binding along with mesoporous network of MIL-101Cr can be found in our published literature.The mass uptake and uptake rates are measured with cutting edge experimental facilities under a controlled pressure and temperature environment.
1.2 Adsorption Technologies
1.2.1 Adsorption desalination
“The availability of “fresh water” as a search for quenching global thirst remains a pressing concern throughout the world, although most of Earth’s surface is covered by oceans or saline water. The effort of providing fresh water for the world’s inhabitants seems to be moved in the wrong direction, because, according to the World Health Organization (WHO), at least one billion people do not have access to clean and fresh water, and about 41% of earth’s population live in water-stressed areas, which climbs to 3.5 billion by 2025. So, the demands for new sources and technologies of fresh water are needed. To mitigate these requirements, desalination has been a practical solution”.
Adsorption desalination (AD) is a novel method of producing potable water, despite the adsorption cycle, for cooling applications found in chemical, power and co-generation plants. Hitherto, there are several kinds of commercial-scale desalination plants in many water scarce countries, such as the multistage flash (MSF) type; the multi-effect desalination type; the membrane-based reverse osmosis (RO) plants; the hybrid plants, which combine the RO and MSF processes; and electrodialysis (ED) or electrodialysis reversal (EDR). All of the mentioned desalination methods are found to be either highly energy-intensive to maintain the processes of desalination or prone to serious erosion and fouling problems in the evaporating units operating at elevated evaporating temperatures. The AD cycle is proposed to mitigate the shortcomings of the conventional desalination methods. The advantages of the advanced AD cycle are that (i) it employs waste heat at low temperatures for the cycle, temperatures of 85 ºC or lower; (ii) The vaporization of saline or brackish water in the evaporator is kept at a low temperature, typically between 20–25 ºC, to mitigate problems of corrosion and fouling; and (ii) the complete elimination of any bio-contamination by desorption at 65ºC or more where any unwanted aerosol-entrained microbes or cells from the evaporator would be killed. In order to attain optimum and cost effective operation of the studied advanced adsorption desalination cycle, extensive studies have been performed on the design and development of self-generative single spool valve, development of low cost concrete silo pre-treatment of brackish or sea water by ozone micro-bubble, thermophysical properties of carbon nano tubes and other related sub topics. Most of the research work related to adsorption desalination has been conducted in collaboration with many renowned Japanese and overseas colleagues.
1.2.2 Advanced Macro Adsorption Cooling Systems
(i) Multi-stage cycles
The breath of my research interest lies mainly within the field of air conditioning and refrigeration, which involves the design, optimization, construction and demonstration of several innovative thermally driven adsorption (solid/vapor) systems, namely, two–stage adsorption chiller, three–stage adsorption chiller and conventional multi–bed adsorption chiller. These chillers can re–utilize low temperature waste heat for useful cooling applications thereby reducing in environmental pollution (thermal as well as gaseous emissions) as lower fossil fuels inputs are required at the power station. All three innovative systems use silica gel–water as the adsorbent–refrigerant pair. This pair is well suited to low–temperature heat utilization and is environmentally benign. The first two chillers can exploit waste heat around 50ºC in combination with a coolant at 30ºC. No other system can produce cooling energy with this extremely low driving source temperature. W have developed a three-stage adsorption chiller which is operational with driving source temperature as low as 40 deg C along with a coolant at 30 deg C.
Based on the practical knowledge of single and multi-stage adsorption chiller operations, a thermodynamic formulation to calculate the minimum driving heat source temperature of an advanced solid sorption cooling device, and it is validated with experimental data. This formalism has been developed from the rigor of the Boltzmann distribution function and the condensation approximation of adsorptive molecules. Experimental data from single-, two-, and three-stage adsorption chillers are also shown therein. In principle, a ten-stage chiller can be driven with a heat source only 2.2°C above the ambient. It is observed that a heat source at as low as 45°C is enough to drive a three-stage adsorption chiller for producing refrigeration at 7 °C, with condensation at 30 °C.
(ii) Dual-mode, multi-stage non-regenerative, multi-bed regenerative cycle
The main disadvantages of staged regeneration adsorption chillers are their high initial costs and poor performance in terms of chillers coefficient of performance (COP). In order to achieve better performances in adsorption cooling systems, Professor F. Meunier of the CNAM–IFFI of France introduced cascaded adsorption systems. However, Meunier did not focus on low–temperature driven chillers. The system based on Saha et al. (1997) is a low–temperature driven regenerative single–stage, multi–bed chiller. The novel chiller design demonstrates the high efficiency of heat recovery from the heat sources using the serially–connected and multi–bed approach. In another endeavor, we have designed and constructed a dual-mode, multi-bed regenerative and multi-stage non-regenerative chiller.
1.2.3 Energy storage systems
Clean energy has played only a small part in today’s energy picture, but it will contribute significantly in the future. The future of energy systems appears to be dominated by new and emerging technologies such as hydrogen-based technologies, advanced adsorption systems, new photo-voltaic materials, etc. However, hydrogen may require pressurizing the gas which is the simplest approach to hydrogen fuel storage.
Natural gas (NG) is a potentially attractive fuel for automobiles as NG vehicles are environmentally friendly, emitting less carbon dioxide and several other air pollutants. The conventional techniques of using a compressed natural gas (CNG) source (mainly methane) are problematic as high pressures are required. So there is great motivation to develop more efficient low-pressure gas storage systems.
An alternative but promising method of storing hydrogen is to employ the adsorption know-how where the adsorbed system utilizes the vapor uptake properties of adsorbent but at a much lower gas pressures. Adsorbate, such as methane or hydrogen, could be stored at lower pressures but sacrificing marginally on the storage capacity. Highly porous activated carbons are used as adsorbent and the adsorbed phase lowers the pressure in the storage vessel and thus providing higher safety. In the adsorbed form, the quantity of methane storage is comparable to most commercial systems employed to date.
The release of adsorbed NG (mainly methane) is performed by a simple depressurization process or the heating of the container where the required amount of heat is obtained from the exhaust flue gas of the fuel cell where the methane is burnt (found in automobiles). The economic advantages of the proposed Adsorbed natural gas (ANG) storage system sorption are as follows:
(i) Firstly, as the adsorbed phase of NG is stored at a relatively low pressure (typically below 30-40 bars), the wall thicknesses of storage cylinders could be made much thinner than those of CNG (pressure 350 bars). Thus, the low NG pressures ensure greater safety for small storage vessels and the NG could be transported in vehicles to remote regions or for domestic applications.
(ii) A slow gas release rate and a simpler controller are required and the chance of accident is lower.
(iii) Adsorption uptake efficiency is high and system is scaleable for capacity upgrade.
(iv) Ease of transport.
(v) Low temperature for regeneration, even at room temperature.
(vi) Adsorbent lasts several thousand times of re-use.
The following research directions could be conducted in future;
To build-up facilities for measuring the adsorption characteristics and isotherms of promising and new adsorbents such as the activated carbon, activated carbon fibers, MOFs, etc. and these data are useful for hydrogen and methane storage systems. These experiments are essential in determining the energetic performance of hydrogen and methane based adsorption storage. From such experiments, a new and fundamental design, on storage systems would emerge and they could compliment the system modeling studies as well.
Potential applications
(i) The application of natural gas storage employing adsorption phenomena is more attractive. Being charged at low cylinder pressure (less than 30 bars), the distribution of natural gas to domestic consumers and other users in remote regions is much safer as compared to compressed natural gas cylinders where the system pressures tend to be as high as 300 bars which could pose a severe safety problem.
(ii) Its potential applications in automobiles as main energy sources in future when methane acts as the fuel source.
1.3. One of the major problems facing the electronics industry is the thermal management problem where the heat dissipation by conventional fan cooling from a single CPU (Central Processor Unit) chip has reached a bottleneck situation. With increasing heat rejection from higher designed clock speeds, temperatures on the chip surfaces have reached the thermal design point (TDP) of fan-fins cooling devices, about 73o C. A single CPU chip containing both power and logic circuits, can no longer sustain the designed clock speed because of high thermal dissipation. Consequently, major chip manufacturers have embarked on two or more processors designed on a single footprint, distributing the CPU generated heat to a wider area of its casing so as to have a capability for over-clocking. Now a days, a challenge to the thermal management problem of CPUs is the development of cooling systems which can handle not only the level of heat dissipation of computer’s CPU but they should also have the potential of being scaled down or miniaturized without being severely bounded by the thermal bottlenecks of the convective air cooling or boiling.
A central challenge in the cooling science today is the development of miniaturized coolers for electronics cooling purposes, which can revolutionize thermal management of electronics and optoelectronic systems, as well as in the small-scale integration of refrigeration equipment. Thus an important research area is to model and develop miniature cooling devices that is: compact; virtually free of moving parts, highly reliable, free of toxic and environmentally-harmful substances, highly efficient in converting input (electrical power) to cooling power, capable of exceptionally high cooling densities, and available at affordable price. Hence a novel modular and miniature chiller named the pressurized electro-adsorption chiller is proposed that symbiotically combines adsorption and thermoelectric cooling devices. The seemingly low efficiency of each cycle individually is overcome by an amalgamation with the other.
This pressurized electro-adsorption chiller incorporates solely existing technologies. It can attain large cooling densities, yet is free of moving parts and comprises harmless materials. The governing physical processes are primarily surface rather than bulk effects, or involve electron rather than fluid flow. This insensitivity to scale creates promising applications in cooling personal computers and other microelectronic appliances.
1.4. As for an energy efficiency assessment, my research advocates the material re-circulation and thermal energy cascaded system based on innovative technology that recovers waste heat from industrial facilities and transport the recovered energy to satisfy energy demand in the buildings sector. Cost effective energy efficiency assessment will be performed.
1.5. Adsorbed Gas Bulb Temperature Sensor
Upon the availability of additional research grant, I am intending to work on the design and development of an innovative adsorbed gas bulb thermal sensor which is contrived through a judicious combination of a microporous adsorbent and any gas as the filler fluid and can be used in a range of temperatures from cryogenic to several 100’s of oC. The sensor is filled with a highly micro-porous adsorbent such as activated carbon (AC) which can be in powder or granule form and an adsorbate which can be any fluid such as carbon dioxide, nitrogen or methane. The pressure changes derived from isosteric heating/cooling of the sensor bulb are used as inputs for control elements. A link between the fully reversible adsorbent and adsorbent characteristics and required sensitivity of the bulb at a specified operating temperature form important components of this study. Thus, the proposed study will be a boon for temperature indication and control in virtually every field. The key characteristics of the study are: (i) adoption of a sensor bulb which is almost comparable in size to the existing vapor pressure sensors, (ii) utilization of pressure changes brought out by constant uptake heating and cooling of the bulb, (iii) ability to choose the gas + adsorbent combination based on the response required at a given temperature range (iv) avoidance of problems associated with the absence of sensor output in the event of a process going outside the range of specified operation, (iv) adoption of commercially available activated carbons and any gas, and (v) avoiding crushing of the bulb because it is filled with a powder.
1.1 Adsorption Sciences
(i) A theoretical framework for the estimation of the isosteric heat of adsorption between an adsorbate (vapor) and an adsorbent (solid) is proposed based on the thermodynamic requirements of chemical equilibrium, Maxwell relations and the entropy of the adsorbed phase. The derived equation for the isosteric heat of adsorption is verified against three sets of judiciously selected adsorbent + adsorbate data that are found in the literature and the predictions are found to agree within the experimental uncertainties of the reported data.
(ii) A thermodynamic framework for calculating the specific heat capacity of a single component adsorbent + adsorbate system has been derived and developed using the classical thermodynamics, and these are essential for the design of adsorption processes. The derived formulation of the is compared with experimentally measured of adsorbent + adsorbate systems. The purpose of this letter is to fill up the information gap with respect to the state of adsorbed phase to dispel the confusion as to what is the actual state of the adsorbed phase.
(iii) We have developed the complete thermodynamic property fields for a single-component adsorbent + adsorbate system. These equations enable us to compute for the actual specific heat capacity, partial enthalpy and entropy which are essential for the analyses of single-component adsorption processes.
(iv) A considerable progress has been made for the development of novel porous materials with controlled architectures and surface treatment. An important feature of these adsorbent materials is the maximization of adsorption capacity at Henry’s region. A thermodynamic framework is presented to capture the relationship between the pore specific surface areas with the enthalpy of adsorption. Using this approach, the scientific community can be guided to the development of advanced porous adsorbent and adsorbate pairs. The adsorbents with the highest porous surface areas tend to possess lower isosteric heat of adsorption when storing the methane and hydrogen gases at room temperature.
1.1.1 Adsorption isotherms and kinetics
The adsorption characteristics of (i) pure water vapor on two different types of parent silica gels of type “RD” and “A” and Cu sputtered silica gel, (ii) n-butane, methane, R134a and R507A on functional activated carbon (Maxsorb III), and (iii) ethanol on activated carbon fiber (ACF) of types A-15 and A-20 at temperatures from 273 to 338 K and at different equilibrium pressures are experimentally studied by a volumetric technique and a thermo-gravimetric analyzer (TGA). The thermophysical properties such as skeletal density, BET surface area, pore size, pore volume and the total porosity of silica gel, Maxsorb III are determined.
We have measured experimentally the adsorption kinetics of (i) water on silica gel (type RD, cu-sputtered RD), (ii) ethanol and methanol on pitch-based activated carbon, activated carbon fibers, (iii) ethanol on to surface treated parent activated carbons and (iv) ethanol on Metal Organic Frameworks material namely MIL-101Cr, at different adsorption temperatures ranging from 27 to 70°C, which are suitable for adsorption chiller design. The ligand and metal binding along with mesoporous network of MIL-101Cr can be found in our published literature.The mass uptake and uptake rates are measured with cutting edge experimental facilities under a controlled pressure and temperature environment.
1.2 Adsorption Technologies
1.2.1 Adsorption desalination
“The availability of “fresh water” as a search for quenching global thirst remains a pressing concern throughout the world, although most of Earth’s surface is covered by oceans or saline water. The effort of providing fresh water for the world’s inhabitants seems to be moved in the wrong direction, because, according to the World Health Organization (WHO), at least one billion people do not have access to clean and fresh water, and about 41% of earth’s population live in water-stressed areas, which climbs to 3.5 billion by 2025. So, the demands for new sources and technologies of fresh water are needed. To mitigate these requirements, desalination has been a practical solution”.
Adsorption desalination (AD) is a novel method of producing potable water, despite the adsorption cycle, for cooling applications found in chemical, power and co-generation plants. Hitherto, there are several kinds of commercial-scale desalination plants in many water scarce countries, such as the multistage flash (MSF) type; the multi-effect desalination type; the membrane-based reverse osmosis (RO) plants; the hybrid plants, which combine the RO and MSF processes; and electrodialysis (ED) or electrodialysis reversal (EDR). All of the mentioned desalination methods are found to be either highly energy-intensive to maintain the processes of desalination or prone to serious erosion and fouling problems in the evaporating units operating at elevated evaporating temperatures. The AD cycle is proposed to mitigate the shortcomings of the conventional desalination methods. The advantages of the advanced AD cycle are that (i) it employs waste heat at low temperatures for the cycle, temperatures of 85 ºC or lower; (ii) The vaporization of saline or brackish water in the evaporator is kept at a low temperature, typically between 20–25 ºC, to mitigate problems of corrosion and fouling; and (ii) the complete elimination of any bio-contamination by desorption at 65ºC or more where any unwanted aerosol-entrained microbes or cells from the evaporator would be killed. In order to attain optimum and cost effective operation of the studied advanced adsorption desalination cycle, extensive studies have been performed on the design and development of self-generative single spool valve, development of low cost concrete silo pre-treatment of brackish or sea water by ozone micro-bubble, thermophysical properties of carbon nano tubes and other related sub topics. Most of the research work related to adsorption desalination has been conducted in collaboration with many renowned Japanese and overseas colleagues.
1.2.2 Advanced Macro Adsorption Cooling Systems
(i) Multi-stage cycles
The breath of my research interest lies mainly within the field of air conditioning and refrigeration, which involves the design, optimization, construction and demonstration of several innovative thermally driven adsorption (solid/vapor) systems, namely, two–stage adsorption chiller, three–stage adsorption chiller and conventional multi–bed adsorption chiller. These chillers can re–utilize low temperature waste heat for useful cooling applications thereby reducing in environmental pollution (thermal as well as gaseous emissions) as lower fossil fuels inputs are required at the power station. All three innovative systems use silica gel–water as the adsorbent–refrigerant pair. This pair is well suited to low–temperature heat utilization and is environmentally benign. The first two chillers can exploit waste heat around 50ºC in combination with a coolant at 30ºC. No other system can produce cooling energy with this extremely low driving source temperature. W have developed a three-stage adsorption chiller which is operational with driving source temperature as low as 40 deg C along with a coolant at 30 deg C.
Based on the practical knowledge of single and multi-stage adsorption chiller operations, a thermodynamic formulation to calculate the minimum driving heat source temperature of an advanced solid sorption cooling device, and it is validated with experimental data. This formalism has been developed from the rigor of the Boltzmann distribution function and the condensation approximation of adsorptive molecules. Experimental data from single-, two-, and three-stage adsorption chillers are also shown therein. In principle, a ten-stage chiller can be driven with a heat source only 2.2°C above the ambient. It is observed that a heat source at as low as 45°C is enough to drive a three-stage adsorption chiller for producing refrigeration at 7 °C, with condensation at 30 °C.
(ii) Dual-mode, multi-stage non-regenerative, multi-bed regenerative cycle
The main disadvantages of staged regeneration adsorption chillers are their high initial costs and poor performance in terms of chillers coefficient of performance (COP). In order to achieve better performances in adsorption cooling systems, Professor F. Meunier of the CNAM–IFFI of France introduced cascaded adsorption systems. However, Meunier did not focus on low–temperature driven chillers. The system based on Saha et al. (1997) is a low–temperature driven regenerative single–stage, multi–bed chiller. The novel chiller design demonstrates the high efficiency of heat recovery from the heat sources using the serially–connected and multi–bed approach. In another endeavor, we have designed and constructed a dual-mode, multi-bed regenerative and multi-stage non-regenerative chiller.
1.2.3 Energy storage systems
Clean energy has played only a small part in today’s energy picture, but it will contribute significantly in the future. The future of energy systems appears to be dominated by new and emerging technologies such as hydrogen-based technologies, advanced adsorption systems, new photo-voltaic materials, etc. However, hydrogen may require pressurizing the gas which is the simplest approach to hydrogen fuel storage.
Natural gas (NG) is a potentially attractive fuel for automobiles as NG vehicles are environmentally friendly, emitting less carbon dioxide and several other air pollutants. The conventional techniques of using a compressed natural gas (CNG) source (mainly methane) are problematic as high pressures are required. So there is great motivation to develop more efficient low-pressure gas storage systems.
An alternative but promising method of storing hydrogen is to employ the adsorption know-how where the adsorbed system utilizes the vapor uptake properties of adsorbent but at a much lower gas pressures. Adsorbate, such as methane or hydrogen, could be stored at lower pressures but sacrificing marginally on the storage capacity. Highly porous activated carbons are used as adsorbent and the adsorbed phase lowers the pressure in the storage vessel and thus providing higher safety. In the adsorbed form, the quantity of methane storage is comparable to most commercial systems employed to date.
The release of adsorbed NG (mainly methane) is performed by a simple depressurization process or the heating of the container where the required amount of heat is obtained from the exhaust flue gas of the fuel cell where the methane is burnt (found in automobiles). The economic advantages of the proposed Adsorbed natural gas (ANG) storage system sorption are as follows:
(i) Firstly, as the adsorbed phase of NG is stored at a relatively low pressure (typically below 30-40 bars), the wall thicknesses of storage cylinders could be made much thinner than those of CNG (pressure 350 bars). Thus, the low NG pressures ensure greater safety for small storage vessels and the NG could be transported in vehicles to remote regions or for domestic applications.
(ii) A slow gas release rate and a simpler controller are required and the chance of accident is lower.
(iii) Adsorption uptake efficiency is high and system is scaleable for capacity upgrade.
(iv) Ease of transport.
(v) Low temperature for regeneration, even at room temperature.
(vi) Adsorbent lasts several thousand times of re-use.
The following research directions could be conducted in future;
To build-up facilities for measuring the adsorption characteristics and isotherms of promising and new adsorbents such as the activated carbon, activated carbon fibers, MOFs, etc. and these data are useful for hydrogen and methane storage systems. These experiments are essential in determining the energetic performance of hydrogen and methane based adsorption storage. From such experiments, a new and fundamental design, on storage systems would emerge and they could compliment the system modeling studies as well.
Potential applications
(i) The application of natural gas storage employing adsorption phenomena is more attractive. Being charged at low cylinder pressure (less than 30 bars), the distribution of natural gas to domestic consumers and other users in remote regions is much safer as compared to compressed natural gas cylinders where the system pressures tend to be as high as 300 bars which could pose a severe safety problem.
(ii) Its potential applications in automobiles as main energy sources in future when methane acts as the fuel source.
1.3. One of the major problems facing the electronics industry is the thermal management problem where the heat dissipation by conventional fan cooling from a single CPU (Central Processor Unit) chip has reached a bottleneck situation. With increasing heat rejection from higher designed clock speeds, temperatures on the chip surfaces have reached the thermal design point (TDP) of fan-fins cooling devices, about 73o C. A single CPU chip containing both power and logic circuits, can no longer sustain the designed clock speed because of high thermal dissipation. Consequently, major chip manufacturers have embarked on two or more processors designed on a single footprint, distributing the CPU generated heat to a wider area of its casing so as to have a capability for over-clocking. Now a days, a challenge to the thermal management problem of CPUs is the development of cooling systems which can handle not only the level of heat dissipation of computer’s CPU but they should also have the potential of being scaled down or miniaturized without being severely bounded by the thermal bottlenecks of the convective air cooling or boiling.
A central challenge in the cooling science today is the development of miniaturized coolers for electronics cooling purposes, which can revolutionize thermal management of electronics and optoelectronic systems, as well as in the small-scale integration of refrigeration equipment. Thus an important research area is to model and develop miniature cooling devices that is: compact; virtually free of moving parts, highly reliable, free of toxic and environmentally-harmful substances, highly efficient in converting input (electrical power) to cooling power, capable of exceptionally high cooling densities, and available at affordable price. Hence a novel modular and miniature chiller named the pressurized electro-adsorption chiller is proposed that symbiotically combines adsorption and thermoelectric cooling devices. The seemingly low efficiency of each cycle individually is overcome by an amalgamation with the other.
This pressurized electro-adsorption chiller incorporates solely existing technologies. It can attain large cooling densities, yet is free of moving parts and comprises harmless materials. The governing physical processes are primarily surface rather than bulk effects, or involve electron rather than fluid flow. This insensitivity to scale creates promising applications in cooling personal computers and other microelectronic appliances.
1.4. As for an energy efficiency assessment, my research advocates the material re-circulation and thermal energy cascaded system based on innovative technology that recovers waste heat from industrial facilities and transport the recovered energy to satisfy energy demand in the buildings sector. Cost effective energy efficiency assessment will be performed.
1.5. Adsorbed Gas Bulb Temperature Sensor
Upon the availability of additional research grant, I am intending to work on the design and development of an innovative adsorbed gas bulb thermal sensor which is contrived through a judicious combination of a microporous adsorbent and any gas as the filler fluid and can be used in a range of temperatures from cryogenic to several 100’s of oC. The sensor is filled with a highly micro-porous adsorbent such as activated carbon (AC) which can be in powder or granule form and an adsorbate which can be any fluid such as carbon dioxide, nitrogen or methane. The pressure changes derived from isosteric heating/cooling of the sensor bulb are used as inputs for control elements. A link between the fully reversible adsorbent and adsorbent characteristics and required sensitivity of the bulb at a specified operating temperature form important components of this study. Thus, the proposed study will be a boon for temperature indication and control in virtually every field. The key characteristics of the study are: (i) adoption of a sensor bulb which is almost comparable in size to the existing vapor pressure sensors, (ii) utilization of pressure changes brought out by constant uptake heating and cooling of the bulb, (iii) ability to choose the gas + adsorbent combination based on the response required at a given temperature range (iv) avoidance of problems associated with the absence of sensor output in the event of a process going outside the range of specified operation, (iv) adoption of commercially available activated carbons and any gas, and (v) avoiding crushing of the bulb because it is filled with a powder.
Research
Research Interests
Membership in Academic Society
- Utilizing adsorbed CO2 for fast algae cultivation and biofuel extraction
keyword : adsorption, algae, biofuel, CO2
2021.11~2024.03. - Utilizing adsorbed CO2 for fast algae cultivation and biofuel extraction
keyword : adsorption, algae, biofuel, CO2 adsorption
2022.01~2024.12. - Utilizing Adsorbed CO2 for Fast Algae Cultivation and Biofuel Extraction
keyword : adsorption, algae, biofuel, CO2
2021.11~2023.03. - Pore tailored and surface modified functional activated carbons for selective CO2 capture
keyword : activated carbon, adsorption, CO2 capture, functional group, pore tailoring, surface treatment.
2020.06~2023.06. - Development of activated carbon based composite adsorbent materials
keyword : adsorption, composite, cooling
2013.09~2016.09. - Development of Waste Heat-Driven Potable Water Production System
keyword : Desalination, adsorption, waste heat utilization
2010.10~2015.10.
- Research on high-speed cultivation of Nori using high-concentration gas dissolution technology
- Studied the development of a device with a combined hybrid mechanical vapor compression - adsorption cycle, particularly to devices used in moisture or temperature control applications that incorporate or embody refrigeration or heat pump cycles for example HVAC applications.
- Verification of adsorption performance in adsorption cooling system
- This study deals with the development of exhaust heat powered next generation adsorption cooing system for automobile air conditioning applications.
- Heat and mass transfer at solid-gas-liquid interface, such as evaporation, condensation and adsorption, strongly influences the performance of various energy systems. The present study proposes a new scientific discipline "Meta-Fluidics" pursuing transcendence of conventional performance of the systems by making use of nanostructures of interface. Optimum design of complex nanosturucture with the aid of knowledge from the meta-fluidics will be capable of creating innovative high-efficiency heat/mass transfer surfaces, which goes beyond the conventional macroscale measure of interface characteristics.
- Quenching global thirst by adsorption desalination (AD), which (as patented by the authors,) is a practical and inexpensive method of desalinating the saline and brackish water to produce fresh water for agriculture irrigation, industrial and building applications. The AD cycle consumes the lowest specific energy per unit volume of product water, and we have devised an advanced AD cycle to achieve 1.5 kWh/m3 benchmark. As compared with other desalination methods, the AD cycle has the unique advantages, namely (i) the utilization of renewable or waste heat sources at temperatures below 85 deg C, (ii) low corrosion and fouling rates on the tube materials due to the evaporation of saline water at low temperature (typically below 35 deg C), (iii) it has no major moving parts which renders low maintenance cost, and (iv) the adsorbent is silica gel which is available in nature.
- This international joint research project relates to the design of an adsorption cycle for the purpose of producing water of suitable quality from the saline or brackish water and the water could be used for both industrial and potable purposes. The unique features of this project are that it utilizes; (i) a low temperature heat source, (ii) a low temperature within the evaporator unit where water vapor is separated from the solution and (iii) the modular cum flexible cyclic-steady operation of the adsorbent-adsorbate towers. In this proposed design, it has been estimated that the specific water yield from the cyclic-steady operation of the silica-gel water adsorption desalination plant is about 6 cubic meter of water per day per tonne of adsorbent.
- A multi-bed multi-stage adsorption chiller is proposed and studied. The chiller is automatically switching between conventional and multi-stage modes, and thus optimized for alternating temperatures of various heat sources.
An experimental prototype of our proposed chiller is built to investigate the performance of the chiller and to determine the driving heat source temperature levels of various modes of the chiller. The simulation codes of different modes are also developed to investigate the design and operating conditions of chiller. It is seen that the two-stage and three-stage mode of the chiller could run with very low heat source temperature (40 to 60 deg C). Though the COP (Coefficient of performance) of three-stage and two-stage mode is quit low, however, the system is effective to utilize low grade waste/renewable heat source, which finally contributes to mitigation of global warming. An advanced single stage called "mass recovery cycle" is also studied. It is proved that the single-stage cycle with mass recovery process improve the cooling capacity of the chiller.
The performance of adsorption chiller mainly depends on the heat and mass transfer characteristics of the adsorbent materials. The study also investigates the heat and mass transfer characteristics of adsorbent materials such as, silica gel and carbon fiber. - The revised scope of this work is focused mainly on the prototype development of a miniature Electro-Adsorption chiller with a footprint of a few cm squared. This entails the use of the state-of-the-art MEMS/NEMS fabrication techniques as well as advanced thin-film technology
Books
Reports
Papers
Presentations
- Bangladesh Physical Society
- Indian Society of Heat and Mass Transfer
Educational
Educational Activities
I have been working at the International Institute for Carbon-Neutral Energy Research, Kyushu University. I am also working as a professor of the Mechanical Engineering Department of Kyushu University and Adjunct Profesor at the Interdisciplinary Graduate School of Engineer Sciences, Kyushu University. I am conducting one course for graduate students and several courses related to postgraduate students research and educational activities, which includes:
Graduate Course:
(1) Advanced Thermal Engineering
(2) Seminar in Thermal Engineering
(3) Mechanical Engineering Research Planning
and a two credit course on clean energy technologies for postgraduate students of Faculty of Engineering.
Other Educational Activities
Graduate Course:
(1) Advanced Thermal Engineering
(2) Seminar in Thermal Engineering
(3) Mechanical Engineering Research Planning
and a two credit course on clean energy technologies for postgraduate students of Faculty of Engineering.
- 2022.06.
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