担当区分：筆頭著者,　最終著者,　責任著者   記述言語：日本語   出版者・発行元：Refrigeration Science and Technology  

This work focuses on experimental assessment of nano-tailored microporous silica doped with 1.5 % of aluminium in adsorption chiller application. The mean pore size of the selected material is ~1.8 nm. The addition of aluminium shows a significant increment of the adsorption of water in the experimental setup in the lower region of adsorption. The tested amount was approximately 100 grams in a closed-loop one cycle adsorption chiller system in a fully controlled environment to test the energy output and energy capacity of the material in combination with the water evaporative cooling in downscaled system. The material was tested under different conditions focusing on input temperature and cooling output at different flowrates. Compared to the theoretical values based on the measurements of adsorption isotherms the actual experimental values exhibit diminution in all parameters due to various thermal losses in the practical system. The potential of the material, however, shows better results in comparison to many other typical adsorption materials for this application such as silica gel and some zeolitic materials.

DOI： 10.18462/iir.gl.2020.1201

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society of Refrigerating and Air Conditioning Engineers  

<p>Nanotailored microporous silica represents one of the more recent artificially prepared advanced materials used in heat transformation and conservation field after silica gel and various zeolite and zeolite-like materials. In this work, we introduce experimental findings on the energy characteristics of water adsorption on nanotailored microporous silica with 1.5 % aluminium doping in the structure. The downscaled system in this work simulates actual working conditions in a controlled environment for both heating and cooling mode. The key properties of this material lie in the regeneration temperatures 60 to 80 ℃ and COP, which reaches values around 0.6 in case of cooling and 0.7 in case of heating. In absolute values at Δ<i>T</i> = 15 ℃, the system reaches storing capacities of about 90 Wh and 126 Wh per adsorbent kilogram in terms of cooling and heating potential energy, respectively. An important factor of kinetic influence on system performance is discussed on a basis of constant time experiment and time-dependent energy flow breakthrough analysis. Constraining factors are found to be in parallel through the driving force of the pressure swing as well as the heat transfer through the body of the adsorption bed.</p>

DOI： 10.11322/tjsrae.21-37DE_EM_OA

CiNii Research

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Sustainable Energy Technologies and Assessments  

Humidification-dehumidification desalination (HDD) systems offer a feasible approach for the production of fresh water in inaccessible areas as they can be operational using renewable energy and require little maintenance. Various studies are being carried out to boost the system performance. In this paper, an open air open water HDD system is proposed that exploits the enhanced evaporation and condensation processes by implementing with the Maisotsenko cycle (M-cycle). The system utilizes solar energy as the energy input to heat the saline water. A thermodynamic model is formulated under steady-state conditions, considering the first and second law of thermodynamics. The energetic and exergetic performance of the system is studied. The model is first validated with the experimental data and a good agreement is found where the maximum discrepancy is about 6.0 %. Effects of different operating conditions on key performance parameters such as the Gain Output Ratio (GOR), specific energy consumption (SEC), exergy destruction, and exergy efficiency are analyzed. An improvement is observed in the GOR when the inlet air temperature is raised at constant humidity ratio. The system exhibits better performance in dry air environment when compared with humid air environment. The analysis shows a maximum mass flow rate of desalinated water of 22.3 kg/h, recovery ratio (RR) of 0.223, GOR of 3, SEC of 0.23 kWh/kg and an exergy efficiency of 43.21 %.

DOI： 10.1016/j.seta.2022.102141

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：International Journal of Sustainable Energy  

This paper presents a comparative analysis of the potential working fluids for a promising thermodynamic cycle (Thermal Power Pump cycle) for the utilisation of low-grade heat. The cycle was analyzed along with nucleate boiling correlations and film condensation analysis for variable heat source temperatures (50–150°C) using nine potential working fluids. The working fluids showed varying degrees of cycle performance and system size requirements. Among the working fluids, cyclopentane seems to be an attractive choice of working fluid, due to its superior cycle performance over the wide range of heat source temperatures with moderate system size requirements. For temperatures above 146°C and below 60°C, water and n-pentane are selected, respectively. Working fluids with stronger molecular forces seem to approach the properties of an ideal working fluid for better performance of the system.

DOI： 10.1080/14786451.2021.1924717

Web of Science

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society of Refrigerating and Air Conditioning Engineers  

<p>Water vapor adsorption on activated carbon (AC) for dehumidification purposes has gained much attention due to the abundance of benefits provided by AC. The working region limited in high water vapor relative pressure (<i>P/P0</i>) makes this material suitable only for removing water vapor at a highly humid region. In this study, ozone oxidation was conducted to introduce more oxygen-based functional groups on AC to attract more water molecules. Based on surface characterization results, ozone oxidation increases oxygen functional groups such as carboxylic on AC but decreases their pores. The more AC exposed to ozone, the more different properties could be observed. The increment of functional groups enhances the water vapor adsorption uptake at <i>P/P0</i> ≤ 0.6, shifting the water sorption into lower <i>P/P0</i>.</p>

DOI： 10.11322/tjsrae.21-36DE_EM_OA

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人日本機械学会・社団法人日本伝熱学会  

Renewable energy-based microgrid systems are widely being studied as electrification methods for rural communities in developing countries. Waste heat generated by the components of the microgrid systems, such as the biogas driven generators (BDG), presents the potential of utilizing the low-grade heat in a way that can contribute to the sustainability of such energy systems. From the points of view of affordability, local manufacturability, and applicability for agriculture, thermally driven pumps (TDP) may be attractive for coupling with such microgrid systems. Therefore, the current study has focused on the development of a new type of thermally driven pumping system as a potential waste heat utilization component for microgrid applications in rural areas. A liquid piston-type TDP concept without moving parts, except few valves, was developed and parametric experimental investigations were carried out. The performance and characteristics of the system were studied, which revealed that the proposed system has a superior performance compared to the literature. It was also found that the system performance strongly depends on the heat addition rate and delivery capacity of the system, which are suitable characteristics for the intended application. Hence, the experimental data were used to estimate whether the proposed system can pump enough water that needs to be supplied for the biogas production to supply a 10 kW BDG unit of a microgrid. It was found that 87 – 93% of the total pumped water (13 – 27 m3) would be available for agricultural and other purposes while only 6 – 13% would need to be fed to the biogas digester. Generally, the results seem to be promising, and yet there are potentials for the optimization and improvement of the proposed system, hence they have been pointed out.

DOI： 10.1299/jtst.21-00323

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Thermal Analysis and Calorimetry  

The desiccant dehumidification system can separate the latent heat and sensible heat in the air-conditioning system and achieve energy savings by removing latent heat. Industrial waste heat and renewable energy could be utilized in desiccant dehumidification systems, where the desorption process can be performed below 70 °C. The vapor pressure and temperature of the regenerating air dictate the desorption process corresponding to the isotherm properties. This study has focused on the effects of various temperatures and humidity ratios of regeneration air on the performance of a desiccant dehumidifier using a polymer as an adsorbent. Experiments were performed using the regeneration air with the humidity ratios of 0.005 kg kg−1, 0.010 kg kg−1, 0.015 kg kg−1, and 0.020 kg kg−1, while the air temperatures were varied from 40 °C to 70 °C. The evaluation of this study employs the adsorption/desorption amount, average moisture removal capacity, and latent energy ratio (LER) of the regeneration process as key performance indexes. At the regeneration temperature of 68 °C, the peak desorption amount at the humidity ratio of 0.005 kg kg−1 and 0.010 kg kg−1 both reached 0.011 kg kg−1. The results indicated that the higher desorption temperature led to a higher desorption amount. Besides, with the increased desorption temperature, the average moisture removal capacity increases. In contrast, the high humidity ratio of regeneration air resulted in a weak dehumidification ability. Lower regeneration temperature was difficult to apply to regenerate the polymer-based desiccant under a high-humidity-ratio atmosphere. To attain a high LER, a lower humidity ratio of dry air and regeneration temperature was preferred. The regeneration air with a humidity ratio of 0.020 kg kg−1 is not suitable to apply in the dehumidification system in the temperature range of 40–70 °C.

DOI： 10.1007/s10973-022-11368-7

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Energy Reports  

Desiccant dehumidification systems can be utilized for decoupling moisture removal duty from the conventional mechanical vapor compression systems. Dehumidification using desiccant dehumidifiers is expected to exhibit a better energy efficiency. However, the high energy needed in the regeneration process limits its applicability. To realize the full potential of this technology, it is necessary to develop materials that can be regenerated using heat sources under 70 °C. In this study, activated carbons (ACs) derived from waste biomass were developed as desiccant materials. The ability of activated carbon (AC) to remove the moisture was controlled by carefully preparing the material to achieve the right operation window for optimum moisture sorption processes. The porous and surface characteristics of the newly-prepared AC were analyzed and compared with those of silica gel. The adsorption isotherm measurements were conducted, and the data were fitted with Henry–Sips and Do–Do isotherm models. The current ACs exhibit an excellent water adsorption capacity (up to 0.41 g/g). The efficacy of the ACs for dehumidification applications was assessed using the weather data from several regions of Indonesia, from North Sumatera to Papua. The results revealed that under the studied conditions, the new desiccant material showed a better dehumidification capacity than silica gel. Moreover, the reported AC can be regenerated using temperatures as low as 40 °C, which is readily available from waste heat, including the heat rejection from the condenser of an air-conditioning unit.

DOI： 10.1016/j.egyr.2021.09.003

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：International Journal of Refrigeration  

Indoor air humidity plays a vital role in determining occupants’ health and industrial product quality. Removing excess humidity by adsorption dehumidification is still facing a challenge in finding a suitable material with high adsorption capacity and low regeneration temperature. In this study, the theoretical dehumidification capacity of prepared acorn nutshell-based activated carbons was calculated and compared with silica gel type RD and RD-2060. The calculation was based on the outdoor air condition in two Asian capital cities: Jakarta and Tokyo. The theoretical study found that prepared activated carbon has better dehumidification performance under Jakarta conditions using regeneration temperatures of less than 60°C. Under Tokyo conditions, activated carbon shows auspicious performance during the summer season. Compared with silica gels, acorn nutshell-based activated carbon has a better dehumidification capacity to process high humidity ambient air with a lower regeneration temperature.

DOI： 10.1016/j.ijrefrig.2021.08.012

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Applied Sciences (Switzerland)  

In this study, we evaluated the performance of low Global Warming Potential (GWP) refrigerant R1234yf on the activated carbon (MSC‐30) for adsorption heating applications. The ad-sorption isotherms of MSC‐30/R1234yf were measured using a constant‐volume–variable‐pressure (CVVP) method from very low relative pressure to the practical operating ranges. The data were fitted with several isotherm models using non‐linear curve fitting. An improved equilibrium model was employed to investigate the influence of dead thermal masses, i.e., the heat exchanger assembly and the non‐adsorbing part of the adsorbent. The model employed the model for the isosteric heat of adsorption where the adsorbed phase volume was accounted for. The performance of the heat pump was compared with MSC‐30/R134a pair using the data from the literature. The analysis cov-ered the desorption temperature ranging from 60 °C to 90 °C, with the evaporation temperature at 5 °C and the adsorption temperature and condensation temperature set to 30 °C. It was observed that the adsorption isotherms of R1234yf on MSC‐30 were relatively lower than those of R134a by approximately 12%. The coefficient of performance (COP) of the selected pair was found to vary from 0.03 to 0.35 depending on the heat source temperature. We demonstrated that due to lower latent heat, MSC‐30/R1234yf pair exhibits slightly lower cycle performance compared to the MSC‐ 30/R134a pair. However, the widespread adaptation of environmentally friendly R1234yf in auto-mobile heat pump systems may call for the implementation of adsorption systems such as the direct hybridization using a single refrigerant. The isotherm and performance data presented in this work will be essential for such applications.

DOI： 10.3390/app11052279

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：International Journal of Refrigeration  

Adsorption cycles have been gaining significant interest in waste-heat recovery and renewable energy utilization. Adsorption isotherm data and the equilibrium cycle analysis are crucial steps in evaluating a typical adsorbent + adsorbate pair. In this paper, the performance of Maxsorb III + R245fa and spherical activated carbon, SAC-2 + R245fa were studied for adsorption cooling and adsorption heat transformer (AHT) cycles. Adsorption isotherms of these pairs were measured using the constant-volume-variable-pressure apparatus for temperatures ranging from 30 °C to 60 °C, and fitted with the Dubinin–Astakhov (D–A) and the Tóth isotherm model. An improved equilibrium model was developed, accounting the effects of thermal masses. The specific cooling energy (SCE) and the coefficient of performance (COP) of the adsorption cooling cycle were evaluated for various thermal mass to adsorbent mass ratios. It is observed that SAC-2 + R245fa pair offers better SCEs (20 kJ kg−1and 160 kJ kg−1 at 60 °C and 90 °C, respectively) when compared to that of Maxsorb III + R245fa. The impact of thermal mass is found to be significant for all regeneration temperatures for Maxsorb III + R245fa while the deterioration of COP in SAC-2 + R245fa is notable for high regeneration temperatures (> 75 °C). When employed in the AHT cycle, Maxsorb III offers a slightly higher useful heat while SAC-2 provides a better Quh/QQR albeit by a small margin. The Quh/QQR values for both studied pairs are more than 0.6 for all regeneration temperatures for the heat extraction at 120 °C.

DOI： 10.1016/j.ijrefrig.2020.12.005

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Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Energy Reports  

Adsorption thermal energy storage plays a vital role in supporting the availability of renewable energy. Activated carbons produced from local waste biomass have been attracting considerable attention in adsorption technology due to their unique properties and sustainability. However, their limitation in water vapor uptake hinders the practical application of this material. In this work, acorn nutshells were utilized as a base material to produce activated carbon. Air oxidation was performed as a versatile and low-cost technique to enhance the material's properties and water adsorption capacity. By applying air oxidation as a post-treatment during material production, the amount of active functional groups and the water adsorption on activated carbon has been successfully enhanced. From the theoretical calculation, it is found that activated carbon–water working pairs shown promising performance to be used for adsorption thermal energy storage applications. The adsorption of water vapor on the post-treated-activated carbon releases the isosteric heat between 2400 kJ/kg to 2500 kJ/kg. Moreover, this study's working pair can be driven by a temperature of less than 50 °C. From the results, it is confirmed that by controlling the adsorbent's surface properties, activated carbon–water working pairs can be a promising way to provide alternative material and reduce the energy demand for driving the system.

DOI： 10.1016/j.egyr.2020.11.038

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Energies  

A new model of adsorption isotherms Type IV and V is proposed as a basis for theoretical calculations and modelling of adsorption systems such as adsorption heat storage and heat pumps. As the current models have decent yet limited applicability, in this work, we present a new combined model with universal use for micro-mesoporous silica/water adsorption systems. Experimental measurement of adsorption isotherm of water onto seven different samples of micro and mesoporous silica and aluminium-silica were used to fit new adsorption models based on a combination of classical theories and a distribution function related to the pore-size distribution of the selected materials. The fitting was conducted through a repeated non-linear regression using Trust Region Reflective algorithm with weighting factors to compensate for the scalability of the adsorption amount at low relative pressure with optimization of the absolute average deviation fitting parameter. The results display a significant improvement for most of the samples and fitting indicators compared to more common models from the literature with average absolute deviation as low as AAD = 0.0025 g g−1 for material with maximum uptake of q = 0.38 g g−1. The newly suggested model, which is based on a combination of BET theory and adjusted normal distribution function, proved to bring a higher degree of precision and universality for mesoporous silica materials with different levels of hydrophilicity.

DOI： 10.3390/en13164247

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Scopus

記述言語：英語   掲載種別：学位論文（博士）  

DOI： 10.15017/2534478

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Microporous and Mesoporous Materials  

A detailed investigation on the main characteristics was conducted on a novel and unique group of industrially produced mesoporous silica material. Six materials from a TMPS group were selected in the respect to their pore size ranging from 1.8 nm up to 4.2 nm. Four of the selected samples were also made with silica doping making them potentially attractive for water adsorption applications with the advantage of the pore-tuning possibilities for specific use. The surface area, pore volume and pore size distribution of these materials were established by standard nitrogen adsorption at T = 77.4 K showing typical values of mesoporous silica materials such as high surface area in the range from 600 to 750 m2g−1 and pore volumes reaching 0.38 cm3g−1 in the case of the smallest TMPS-1.5A and 0.98 cm3g−1 in the case of the largest TMPS-4R. The wall thickness was found out regular around 1.5 ~ 2 nm with lower values attributed to bigger pore sized samples promising good structural integrity. Specific heat showed regular values through all the samples at ~ 0.85 J g−1K−1. Additional information on the structural characteristics and the effect on the amount of silanol group presence and the difference on regular and aluminium-doped samples were studied by means of 29Si DD/MAS NMR. Additionally, elemental analysis by EDS was conducted as well. All the characteristics of the TMPS materials were compared to the standard mesoporous silica materials SBA-15 and MCM-41.

DOI： 10.1016/j.micromeso.2019.109644

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Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Adsorption  

Six samples from the TMPS family of mesoporous silica nano-materials from Taiyo Kagaku Co., Ltd. were studied for their potential as a medium for the adsorption thermal energy storage. Selected specimens are distinguished by their pore size from 1.9 to 4.1 nm and aluminium doping. As the adsorbate for the adsorption pair was selected water with the most advantageous properties of high latent heat and safe chemical properties. The tested materials doped with aluminium show high affinity towards the selected adsorbate and high uptakes. The theoretical storage energy density of the materials spans from 700 to 1700 kJ kg−1 based on the adsorption heat. The storage capacity depends mostly on the pore volume and partially on the pore size. The theoretical estimation shows the temperature gain of the adsorption potential as high as ΔT=23∘C for the material TMPS-1.5A with the smallest pore diameter and aluminium doping and as low as ΔT=6∘C for the TMPS-4R with the biggest pore diameter and without aluminium doping.

DOI： 10.1007/s10450-019-00107-4

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Chemical and Engineering Data  

A detailed investigation into the viscosity, density, and refractive index of a binary mixture of propane-1,3-diol/water was performed for the whole range of mass fractions of propane-1,3-diol. The viscosity and density were measured over a wide range of temperatures from T = 253.15 K to T = 353.15 K where possible, or to the nearest safe point before freezing. The refractive indices were measured for the same dilutions as in the case of the viscosity and density over a reduced temperature range of T = (278.15 to 318.15) K. A mathematical analysis via excess properties was conducted and fitted to the Redlich-Kister equation. Furthermore, a prediction of density data is provided by a polynomial and DIPPR exponential model. The viscosity data are fitted to Grunberg-Nissan, Lederer, McAllister, and Heric models and a new combined model with variable temperature and molar and mass fractions based on these models is presented. Data comparison of the propane-1,3-diol/water binary mixture is performed on propan-1,2-diol/water mixture as the physically closest binary system and application alternative fluid.

DOI： 10.1021/acs.jced.8b00403

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.18462/IIR.TPTPR.2017.0112

Web of Science

開催年月日： 2019年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Okinawa   国名：日本国  

開催年月日： 2019年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Fukuoka   国名：日本国  

開催年月日： 2019年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Hradok pri Jelsave   国名：スロバキア共和国  

開催年月日： 2019年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Kanazawa   国名：日本国  

開催年月日： 2019年5月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Vemyslice   国名：チェコ共和国  

開催年月日： 2018年11月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Hradok pri Jelsave   国名：スロバキア共和国  

開催年月日： 2018年11月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Pusan   国名：大韓民国  

開催年月日： 2018年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Fukuoka   国名：日本国  

開催年月日： 2017年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Fukuoka   国名：日本国  

開催年月日： 2017年8月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Tokyo   国名：日本国  

開催年月日： 2017年5月

記述言語：英語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2017年4月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Seol   国名：大韓民国  

開催年月日： 2014年12月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Brno   国名：チェコ共和国  

開催年月日： 2014年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Hrádok   国名：スロバキア共和国  

開催年月日： 2013年5月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Blansko   国名：チェコ共和国  

開催年月日： 2012年10月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Hrádok   国名：スロバキア共和国  

開催年月日： 2012年5月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Hrotovice   国名：チェコ共和国