Regeneration Temperature Research Articles

CO2 Capture with Polyethylenimine Supported on 3D-Printed Porous SiO2 Structures.

Amines supported on porous solid materials have a high CO2 adsorption capacity and low regeneration temperature. However, the high amine load on such substrates and the substrate itself may lead to substantial pressure drop across the reactor. Herein, we compare the CO2 adsorption capacity and pressure drop of fumed silica powder to 3D-printed monolithic fumed silica structures, both functionalized by polyethylenimine (PEI), and find a drastically reduced pressure drop for 3D-printed substrates (0.01 bar vs. 0.76 bar) in the sorption bed with equal CO2 adsorption capacity. Furthermore, the effect of 3D-printing nozzle diameter and PEI loading on the adsorption capacity are investigated and the highest capacities (2.0 mmol/g at 25 °C with 5000 ppm CO2) are achieved with 0.4 mm nozzle size and 34 wt% PEI loading. These high capacities are achieved since the 3D printing and subsequent sintering (700 °C) of monolithic samples does not compromise the surface area of the fumed silica. Finally, the comparison between 3D-printed monoliths and extruded granulate of varying diameter reveals that the ordered channel system of 3D-printed structures is superior to randomly oriented granulate in terms of CO2 adsorption capacity.

Analysis of the Effects of Structural Parameters on the Thermal Performance and System Stability of Ventilation Air Methane-Fueled Reverse-Flow Oxidation Reactors

Ventilation air methane (VAM) from coal mining is a low-grade energy source that can be used in combustion systems to tackle the energy crisis. This work presents a numerical analysis of the thermal and stabilization performance of a VAM-fueled thermal reversal reactor with three fixed beds. The effects of the combustion chamber/regenerator height ratio (β), heat storage materials, and porosity on the oxidation characteristics are evaluated in detail. It is shown that the regenerator temperature tends to vary monotonically with β due to the coupling effect of the gas residence time and heat transfer intensity. The optimal β is determined to be 4/6, above which the system may destabilize. Furthermore, it is found that regardless of the methane volume fraction, the regenerator with mullite inserted has the highest temperature among the heat storage materials investigated. In contrast, the temperature gradually decreases and the system becomes unstable as SiC is adopted, signifying the importance of choosing proper thermal diffusivity. Further analysis reveals that the porosity of the heat storage materials has little effect on the system stability. Decreasing the porosity can effectively reduce the oscillation amplitude of the regenerator temperature, but it also results in greater pressure losses.

Heat and mass transfer analysis of desiccant-coated heat exchanger with desiccants and metal-organic framework for bus air conditioning applications

Desiccant-coated heat exchangers (DCHEs) in air conditioning offer advantages like independent temperature and humidity control, reduced energy consumption, and high performance. However, the availability of desiccants with high water adsorption and low thermal energy requirements is limited. The present study proposes that aluminum fumarate (Al-Fum) MOF-coated heat exchangers will outperform conventional desiccants, especially at low regeneration temperatures (around 50°C). In order to evaluate this hypothesis, the performance of DCHEs was evaluated with a validated analytical model for different solid desiccant coatings: silica gel, zeolite, and Al-Fum MOF. Water vapor sorption characteristics, heat and mass transfer, and adsorption and desorption capacities were determined. The results showed that the Al-Fum MOF-coated heat exchanger outperformed silica gel and zeolite at low regeneration temperatures under adiabatic conditions. The MOF exhibited superior water uptake capacity (0.39 g/g) between 20% and 80% RH compared to the other studied conventional desiccants. Moreover, the MOF achieved the lowest outlet air temperature. At 19.5 g/kgda, the MOF demonstrated higher adsorption rates (4 % and 0.3 %) than zeolite and silica gel. These findings highlight the potential of Al-Fum MOFs as energy-efficient solutions for controlling indoor air humidity, particularly for latent-sensible heat separation systems with conventional vapor compression bus air-conditioning systems.

Transient analysis of an efficient solar assisted air-conditioning system for subtropical climate with various solar thermal collectors

The air conditioning demand of the world is largely fulfilled by vapor compression systems; however, these systems are also responsible for depleting ozone layer due to the nature of refrigerants. Desiccant cooling systems integrated with solar thermal energy technologies could be an attractive alternative with some performance enhancement techniques. In this study, transient seasonal performance investigation is performed for an innovative solar integrated desiccant cooling system that uses regenerative evaporative cooler known as solar assisted desiccant integrated Maisotsenko cycle cooler for better cooling performance. Furthermore, transient annual performance analysis of solar system for meeting thermal energy requirement for regenerating the desiccant wheel in summer season and handling heating load of the building in winter season is also carried out with three different solar thermal collector technologies for finding out more efficient technology. The key performance indicators in this study are useful energy gain, solar source efficiency, auxiliary energy sharing, coefficient of performance, and solar fraction. The results of the key performance parameters are reported as monthly average values. The proposed integrated system resulted to be very efficient with a maximum COP value of 1.13 in April when latent cooling loads are low and 0.78 in August when latent cooling loads are higher. The system’s maximum cooling capacity is 24 kW in April corresponding to a sensible heat factor of 0.720. Furthermore, the regeneration temperature requirements ranged from 50 °C to 78 °C, respectively that makes it favorable to use low grade thermal energy through non concentrating solar thermal collectors. The regeneration thermal energy requirement for desiccant wheel fluctuates throughout the year, maximizing in August due to higher dehumidification requirements. The study also revealed that the evacuated tube collector technology is most suitable with average annual efficiency of around 36 %.

Coupled system for underground heating exchange and solar heat-humidity regulation in greenhouse: Experimental study and simulation analysis

In winter, greenhouses located in mid to high latitudes are required a function of dehumidification and warming due to the low outdoor temperature. Focusing on small spires greenhouses, this study regulates the low temperature and high humidity environment inside the greenhouse and proposes a new-type of greenhouse heat and humidity regulation system by combining composite solid desiccant dehumidification with ground heat exchange system. The greenhouse internal environment is warmed and dehumidified at night by utilizing the adsorption effect of the compound dehumidifier and the sensible heat exchange between the heat exchange system in the ground and the greenhouse. Solar thermal energy is collected during the day using multi-curved tank collector (MTC) for thermal storage in the geothermal system and desiccant desorption. The rationality of pipeline layout is verified through CFD simulation, and the indoor temperature and humidity distribution during the system operation is explored. The experimental results show that the moisture adsorption capacity of the composite desiccant SG-CaCl2 for 10h is 0.511 g/g. The optimal regeneration temperature is 80–100 °C. This system can reduce the nighttime relative humidity of the greenhouse in winter from 96.5 % to 83.6 %, and the average indoor air temperature after warming is 12.8 °C. The heat exchange efficiency of the underground heating exchange system is 0.38. During the desorption phase on daytime, the maximum outlet temperature of MTC is 103.8 °C, and the average heat collection efficiency is 0.42. The system can effectively regulate the air environment in the greenhouse to the appropriate zone for crop growth by combining solar thermal collector technology with recyclable solid dehumidification technology.

Investigation of the impacts of regeneration temperature and methanol substitution rate on the active regeneration of diesel particulate filter in a diesel-methanol dual-fuel engine

Methanol (CH3OH), a sustainable fuel derived from many renewable resources, simultaneously reduces nitrogen oxides (NOx) and particulate matter (PM) in diesel-methanol dual-fuel engines. This study systematically investigated the effects of regeneration temperature and methanol substitution rate (MSR) on the performance of diesel oxidation catalyst (DOC), diesel particulate filter (DPF), and the temperature characteristics of DPF substrate during active regeneration. The experimental results show that the DOC catalytic oxidation of unburned CH3OH has a conversion rate of more than 97.5 % across various MSR. DPF inlet temperature rose faster with higher MSR. Elevated regeneration temperature reduced effective regeneration times and diesel equivalent consumption. Within active regeneration conditions with MSR increases, both effective regeneration times and diesel equivalent consumption initially decreased and then increased as the MSR rose. At MSR = 30 %, the duration of effective regeneration times during DPF active regeneration was minimized, and diesel equivalent consumption at MSR = 30 % experienced an improvement of 22.52 % compared to MSR = 0 %. The highest DPF substrate temperatures across various MSR levels are consistently observed at T6 position within the DPF. This study can provide a theoretical basis for the active regeneration of DPF in methanol-diesel dual-fuel mode.

Performance Investigation and Optimization of Composite Materials in Household Dehumidifiers

The efficiency of household dehumidifiers is affected by air temperature and the temperature used for regeneration. A regeneration temperature that is too high can lead to increased energy use, heat build-up in the desiccant wheel, and lower dehumidification efficiency. In this study, we developed a LiCl@Al-Fum composite material and evaluated it through physical characterization and module testing. The results show that the LiCl@Al-Fum composite with a 20% mass fraction is particularly effective as a desiccant material. Additionally, a 15% volume concentration of neutral silica sol was identified as the optimal binder concentration. A comparative analysis of the effects of glass-fiber desiccant wheels (GF DWs), aluminum desiccant wheels (Al DWs), and commercial desiccant wheels (CM DWs) on household dehumidifier performance revealed that the Al DWs outperformed the CM DWs, showing a 13% improvement in the dehumidification rate and a 12.56% increase in the DCPP. An increase in the dehumidifier structure led to increases in the dehumidification rate by 11.8%, 11.9%, and 10% and in the DCPP by 11.6%, 12.1%, and 10%, respectively. Moreover, the modifications resulted in a 3.85 °C, 3.34 °C, and 3.8 °C decrease in the temperature.

Boosted regeneration of coked SAPO-34 catalyst in MTO fluidized bed reactor by diluted air at elevated temperatures

SAPO-34 zeolite as an excellent catalyst for methanol-to-olefins (MTO) reaction suffers rapid deactivation by prevalent coking. Herein, regeneration of coked-SAPO-34 in a fluidized-bed reactor was successfully intensified by altering temperature (550–650 °C) and oxygen content (7–21 vol.%). Fresh, used, and regenerated catalysts were characterized by different methods to understand the correlation between regeneration conditions, coke content, and catalyst performance. The minor residual coke over the regenerated catalyst comprised active hydrocarbon pool intermediates (like naphthalene, benzaldehyde, phenol, and derivatives), which increased by decreasing regeneration temperature and promoted the selectivity to light olefins at earlier reaction times. The restored microporosity and lifetime of regenerated catalyst were superior by increasing temperature. However, higher attrition at 650 °C, as confirmed by SEM images, caused a partial weight loss of the catalyst and a slight decline in relative crystallinity, hence 600 °C was preferred with additional advantage of less energy consumption. Meanwhile, introducing lower oxygen not only moderated the coke oxidation rate but also enhanced the recovery of beneficial catalytic features for the MTO conversion. Consequently, considering an excellent regeneration as well as lower emission of CO2 detected in the flue gas, diluted air containing 14 vol.% O2 at 600 °C was suggested as the most promising method.

Limits of coefficient of performance of adsorption cooling cycle based on refrigerant’s type

This research work discusses how the thermodynamic properties of refrigerant constrain the upper limit of the coefficient of performance (COP) of adsorption cooling (AC) cycle. A mathematical model is developed based on the mass and energy balance across the adsorption bed and used to estimate the maximum COP. Langmuir model is used to derive the ideal COP. Besides, Carnot COP and exergy efficiency are derived to evaluate the adsorption cooling cycle further. These new parameters are applied to the available cycles in the open literature to assess how much room for improvement is still left in the adsorption technology based on the refrigerant type. Water, ammonia, methanol, ethanol, Butane, R134a, R32, CO2 and R1234ze are used in this study. The maximum cooling COP cannot exceed 1.0 for cooling applications and is always less than 2.0 for heat pumps. Results show that AC cycles using water or ethanol as refrigerants achieve the highest exergy efficiency. The AC cycle using water as an adsorbate and silica gel as an adsorbent has the highest relative COP, about 80 % at 85 °C regeneration temperature. In turn, CO2 exhibits the lowest one. This work is merely an attempt to save experimental effort and time by identifying the most suitable refrigerant based on its physical and thermal properties and the cycle operating conditions.

Solar regenerated carbon-based composite desiccant coated heat exchangers for air dehumidification

Desiccant dehumidification can realize decoupling of latent and sensible heat loads in dehumidified air conditioning, thereby reducing energy consumption. This paper proposes a solar regenerated carbon-based composite desiccant coated heat exchangers (DCHE) for air dehumidification. Carbon-based composite desiccant is electrostatically sprayed onto the surface of the heat exchanger to form a dehumidification coating. An experimental system for evaluating the dehumidification and regeneration performance of DCHE is established. The Taguchi method is employed to evaluate the impact of operating parameters such as air velocity, water flow rate, and regeneration temperature on the dehumidification and regeneration efficiency of DCHE. The result shows that air velocity is the primary factor impacting the dehumidification performance of DCHE, with regeneration temperature and cooling water flow rate following in importance. With the faster air velocity and the lower cooling water flow rate, DCHE shows the better dehumidification performance. Moreover, excessively both high and low regeneration temperatures can result in a degradation in the dehumidification performance of DCHE. Under optimal operating conditions, the dehumidification rate (EDE) and thermal coefficient of performance (COPth) of DCHE can reach 7.5 kg/h and 2.3, respectively. The moisture content of the air reduces from 19.6 g/kg to 8.0 g/kg.

Investigation of purge angle on the air inhomogeneity reduction and energy efficiency improvement of the desiccant wheel dehumidification system

ABSTRACT The rotary desiccant wheel dehumidification system has been extensively applied to achieve deep dehumidification in the modern environment with low humidity ratio. The effect of mixing destruction caused by the temperature and humidity inhomogeneity on the thermodynamic performance of the desiccant wheel deep dehumidification (DWDD) system has not been thoroughly illustrated. This research aims to reduce the mixing destruction and improve the overall energy efficiency of the DWDD system. Numerical analyses were carried out to investigate the mixing destruction characteristics of the deep dehumidification process. The results revealed that the mixing exergy destruction gradually becomes a prominent factor as regeneration temperature and humidity ratio increase under deep dehumidification, and there is a significant temperature and humidity ratio gradient in the transition angles from the regeneration side to the process side. The purge angle is regulated to reduce the average temperature and humidity ratio on the process side and lower the air inhomogeneity. The exergy efficiency of the desiccant wheel can be improved from 44.8% to 73.9% at the regeneration humidity ratio of 20 g/kg under the effective purge angle of 30°, indicating a considerable enhancement of exergy efficiency under the effective purge angle at a high regeneration humidity ratio.

Solar induced low-temperature phase separation in thermomorphic solvents for CO2 capture

Replacing steam with solar for CO2 regeneration is an incredibly promising approach. However, the high temperature required for solvent regeneration and the less-than-optimal photothermal conversion efficiency that prevents reaching the necessary regeneration temperature are significant limitations to this approach. In this work, thermomorphic solvents containing dimethylcyclohexylamine, N-methylcyclohexylamine and photothermal nanoparticles were prepared for CO2 capture. Nano carbon black, multi-walled carbon nanotube and carboxyl group functionalized multi-walled carbon nanotube were used as promoter for photothermal conversion. The experimental results exhibit the high CO2 absorption capacity of 0.1081 g/g solvent for the carboxyl group functionalized multi-walled carbon nanotube based solvent, and it can be efficiently regenerated under solar irradiation at a low temperature of ∼ 323 K. It is noteworthy that the photothermal material not only raise the solution temperature(∼325 K) during solar irradiation but also boosts the CO2 absorption rate, and leads to a ∼ 20.8 % increase in CO2 absorption capacity during the absorption process. Furthermore, the utilisation of photothermal regeneration for thermomorphic solvents can achieve an efficiency of 78.6 %, with a regeneration heat of 2.35 GJ/t CO2, resulting in an energy consumption reduction of approximately 41.1 % in comparison to 30 wt% monoethanolamine. The photo triggered regeneration of the thermomorphic solvent investigated in this study shows promising potential as an energy-efficient carbon capture technology.

Development and analysis of a fiber-optic temperature sensor based on a regenerated fiber Bragg grating

Subject of study. A fiber-optic temperature sensor based on regenerated fiber Bragg gratings is studied. Aim of study. A high-temperature sensor based on a regenerated fiber Bragg grating is developed, and a thermal study of the sensor up to a temperature of 1000°C is performed. Method. The regenerated fiber Bragg grating was produced by annealing a “seed” fiber Bragg grating recorded on SMF-28 hydrogen-loaded optical fiber in a high-temperature muffle furnace at a continuously rising temperature from room temperature to 920°C (the regeneration temperature in the case of SMF-28 fiber). The reflection coefficient of the “seed” grating was as close to 100% as possible, with a structure length of 15 mm. The heating rate was 500 deg/h. Main results. During the work and thermal studies described above, which were performed over a temperature range from +25∘C to +1000∘C with steps of 100°C, a fiber-optic temperature sensor was developed based on a regenerated fiber Bragg grating with a reflectance of about 50% and a temperature sensitivity of 14.9 pm/°C. Practical significance. The proposed method for manufacturing regenerated fiber Bragg gratings enables them to be used as the sensing element in a temperature sensor. The ability to operate at such high temperatures opens up broad potential for application to a wide range of industrial applications (such as gas turbine engines, power plants, steel mills, etc.). This method enables a fiber-optic temperature sensor to be constructed without using additional equipment or materials.

Dual-template synthesis of SFO-type aluminophosphate with enhanced water-sorption-driven cooling performance

Water-based adsorption chillers (ADC) driven by low-grade thermal energy are environment-friendly alternatives to the traditional compression ones to realize the net zero carbon target. Aluminophosphates molecular sieve (AlPOs) is an excellent material for water-based adsorption applications. However, AlPOs suffers from relatively high cost attributed to the extensive use of expensive structure direct agents (SDAs). This study employed a dual-template method, using cheap organic amine as a dual-template, to synthesize low-cost and excellent adsorbent AlPOs with SFO topology (AlPO-SFO). AlPO-SFO synthesized with dual templates shows high crystallinity, large micropore volume, excellent water uptake, and low regeneration temperature. AlPO-SFO guided by 4-dimethylaminopyridine (4-DMAPy) and diethanolamine (DEOA) molar composition of 0.4 and 0.1 exhibits large microporous volume (0.30 ml g−1), high water uptake (0.26 g g−1 at P/P0 = 0.25) and low regeneration temperature (65 °C). Importantly, this AlPO-SFO exhibits a high coefficient of performance (COP) of 0.89 for cooling at a low driven temperature of 64 °C. The additive amine providing alkaline medium ensures the practical synthesis of AlPO-SFO when expensive 4-DMAPy decreases, endowing the 42 % reduction of the raw material cost. The results provide a cheaper synthesis route of AlPO-SFO, which is conducive to its large-scale production as a distinguished adsorbent for adsorption chillers.

Coke Formation and Regeneration during Fe-ZSM-5-Catalyzed Methane Dehydro-Aromatization

Coke formation poses a significant obstacle in the direct conversion of methane into valuable chemicals such as ethylene, benzene, and hydrogen via methane dehydro-aromatization (MDA). At the elevated temperatures necessary for this reaction, coke is the thermodynamically favored product, causing rapid catalyst deactivation and hence necessitating frequent catalyst regeneration. Successful industrial implementation of MDA requires the advancement of catalyst regeneration processes and a comprehensive understanding of coke formation to enhance catalyst performance. Here, we examined the types of coke generated during MDA over a Fe-ZSM-5 catalyst and their impact on deactivation. By combining reactivity studies using catalysts with carefully controlled coke populations with the characterization of the catalyst via XRD, H2-TPR, and pyridine FTIR, we find that soft coke is formed at the Brønsted acid sites, resulting in loss of selectivity, while hard coke is formed at the metal sites causing a loss of activity. While soft coke can be removed at low regeneration temperatures, the removal of hard coke requires harsh conditions which compromise catalyst stability. An investigation into the use of CO2 as an alternative, mild oxidant for catalyst regeneration, however, shows that the mild oxidation strength of CO2 requires even higher regeneration temperatures and hence irreversible loss of Brønsted acid sites.

Experimental parametric evaluation of adsorption characteristics for silica gel - water based open-bed system for seasonal thermal energy storage

This study aims to investigate the potential of using commercial silica gel as an energy storage material in a bulk-scale open bed adsorption-based system to achieve efficient domestic heating using renewable energy sources. Designing an efficient thermal energy storage (TES) system for practical use requires understanding of the sorption properties of the adsorbent and the effects of different operating and physical parameters on the sorption process. One critical parameter that significantly affects the energy storage density when scaling up from a laboratory to a prototype system is the amount of adsorbent in the reactor. Surprisingly, this aspect has been overlooked in previous studies. To address this research gap, a laboratory-scale test rig was designed and constructed. This rig enables the evaluation of the effects of different operating parameters (such as relative humidity, flow rate, and regeneration temperature) and physical parameters (such as the quantity of adsorbent and particle diameter) on the energy storage density of silica gel and the temperature lift in the process. The water adsorption capacity of the silica gel was measured in-house to assist in future theoretical modelling of a prototype TES system. Optimum operating conditions were determined for the system, with a relative humidity of 80 %, an air flow rate of 100 L/min, and material regeneration at 120 °C. The system's performance in terms of material energy storage density and maximum temperature lift was observed for varying amounts of adsorbent, particle diameter, and regeneration temperature at these optimal operating conditions. Finally, the required storage volume to meet domestic space heating demands was estimated based on optimal discharging conditions and compared to other experimental and theoretical studies involving silica gel-based energy storage systems.

New and effective combination of an absorption desalination systems with adsorption and humidification-dehumidification desalination systems utilizing internal heat recovery methods

The fast growth in population and the need for human comfort leads to a significant rise in freshwater shortage and energy usage. This article provides new and effective combinations between absorption (ABDC), adsorption (ADDC), and humidification-dehumidification (HDH) desalination plants. Four new configurations employing different external and internal heat recovery methods between the plants and their components are proposed to enhance the overall system performance, water production, and utilization of the used energy. In all configurations, the solar water heating system is used to power the ABDC. While the ADDC and HDH were powered by the heat recovery from condensation, absorption, or generation processes. Internal heat recovery methods are also applied between the evaporator and condenser in ABDC and ADDC plants to increase energy utilization. The results are evaluated and compared with standalone ABDC results and with previous related studies at different conditions. The production share percentage (%) from each plant for the suggested configurations with regeneration temperatures is also investigated. The maximum water production is achieved by the fourth configuration (3 m3.day−1 with a gain output ratio (GOR) of 1.316 at 120 °C) when the ADDC is worked by the outlet hot water from the ABDC, and internal heat recovery utilized between the condensation and evaporation components of both ABDC and ADDC. The highest GOR is obtained from the second configuration (1.714 at 90 °C). The finding expressed that the proposed configurations have a better performance than traditional ABDC systems. Also, the proposed configurations express another advantage over traditional ABDC, that the configurations have the potential at low-temperature heat sources (55–65 °C) to improve the water productivity to about 455 % and GOR to about 120 %.

Development of a bifunctional material incorporating carbon microspheres for the intensified hydrogen production by sorption-enhanced glycerol steam reforming

Glycerol steam reforming is a green and sustainable alternative to hydrocarbon steam reforming for hydrogen production. Reaction intensification by in-situ CO2 removal using Ni/CaO-based bifunctional sorbent-catalyst materials was investigated in this paper to improve the hydrogen yield and purity significantly. Employing carbon microspheres as the foundation for sorbent synthesis resulted in the development of a hollow CaO sphere sorbent with higher and more stable sorption capacity over multiple adsorption/regeneration cycles compared to sorbents synthesized with conventional methods. The incorporation of different stabilizers improved further the capacity and stability of sorbents. The sorbent materials were tested under different sorption and regeneration temperatures in a dry and wet atmosphere. The intensified sorption-enhanced steam reforming process was evaluated under various reaction temperatures, weight hourly space velocities, and steam-to-carbon molar feed ratios. The bifunctional materials synthesized with carbon microspheres led to improved reaction performances, including a more extended pre-breakthrough period and a more stable behavior during reaction/regeneration cycles.

Performance predication of a solar assisted desiccant air conditioning system using radial basis function neural network: An integrated machine learning approach

In this Paper solar desiccant air conditioning system integrated with cross flow Maisotsenko cycle (M-cycle) indirect evaporative cooler is used to investigate the performance of whole system in different range of parameters. Solar evacuated tube electric heater is used to supply the regeneration temperature to the desiccant wheel, whereas, Desiccant Wheel (DW) and M-cycle is used to handle latent load and sensible load separately. Major contribution of this research is to predict system level performance parameters of a Solar Assisted Desiccant Air Conditioning (Sol-DAC) system using Radial Basis Function Neural Network (RBF-NN) under real transient experimental inlet conditions. Nine parameters are mainly considered as input parameters to train the RBF-NN model, which are, supply Air temperature at the process side of desiccant wheel, supply air humidity ratio at process side of the desiccant wheel, outlet temperature from the desiccant wheel at process side, outlet humidity ratio from the desiccant wheel at process side, regeneration temperature at regeneration side of the DW, outlet temperature from the heat recovery wheel at process side, outlet humidity ratio out from the Heat Recovery Wheel (HRW) at process side, temperature before heat recovery wheel regeneration side of the system, humidity ratio before heat recovery wheel regeneration side of the system. Four parameters are considered as the output of the RBF-NN model, namely: output temperature, output humidity, Cooling Capacity (CC), and Coefficient of Performance (COP). The results of the RBF-NN model shows that the best Mean Squared Error (MSE) and Regression coefficient (R) for outlet temperature prediction are 0.00998279 and 0.99832 when regeneration temperature is 70 °C and inlet humidity at 18 g/kg. Best MSE and R for predication of outlet humidity are 0.0102932 and 0.99485 when the regeneration temperature is 70 °C and inlet humidity at 16 g/kg. Best MSE and R for predication of COP are 0.0106691 and 0.9981 when the regeneration temperature is 70 °C and inlet humidity 12 g/kg. Best MSE and R for predication of CC are 0.0144943 and 0.99711 when the regeneration temperature is 70 °C and inlet humidity 14 g/kg. Experimental and predicted performance parameters were in close agreement and showed minimal deviation. Investigations of predicted results revealed that trained RBF-NN model was capable of predicting the trend of output result under the varying input condition.

Engineering a photothermal responsive cellulose carbon capture material for solar-driven CO2 desorption

The utilization of the solar-driven CO2 desorption of carbon capture materials opens a promising avenue to reduce energy consumption in the carbon capture process. A crucial aspect is the careful coordination of materials' adsorption capacity and regeneration temperature. In this study, a photothermal responsive carbon capture material was developed by incorporating a photothermal responsive cellulose nanofiber matrix skeleton with a temperature-sensitive Pluronic® F-127 and polyethyleneimine. These components formed a staggered network through crosslinking with epichlorohydrin. The devised preparation strategy demonstrated a remarkable conversion rate of 99% for the reaction reagents. The resulting carbon capture material exhibited a high amino density of 14.18 mmol/g and a substantial adsorption capacity of 6.92 mmol/g. Notably, the shrinkage of Pluronic® F-127 molecular chains at elevated temperatures led to an increased surface electrostatic potential and the passivation of amino groups. This transformation endowed the material with a solar-driven regeneration temperature as low as 55 °C, representing an efficient approach to reduce energy consumption during the regeneration process of carbon capture materials.