민재홍

윤도성

두현진

이근정

송주영

송민수

이재원

정재희

박세준

민하예

김대혁

오선희

강문구

정한솔

박종하

박준호

The Plus Energy Innovation Technology Research Center focuses on innovative technologies for plus energy buildings, leading beyond zero-energy building concepts.

플러스에너지혁신기술 연구센터는 제로에너지빌딩을 넘어 미래를 선도하는 플러스 에너지 빌딩 혁신 기술에 중점을 둔다.

Self-assembled pellet adsorbents for sub-ambient direct air capture: from material structuring to system-level optimization

Low waste heat driven indoor CO2 capture via 3D-printed hybrid TPMS monoliths

Ammonia-based thermally regenerative batteries enable waste-heat-powered defrosting

Novel Design of Heat Sinks for Enhanced Chip-Level Cooling in Data Center Servers

Joule-heating regenerable CO2 capture filter: From material to system application

Heat pump assisted direct air capture system for carbon enrichment in plant factory

Sub-ambient transparent radiative liquid cooling system enabling simultaneous solar energy utilization

A review on passive/active technologies towards plus energy building in urban area

Flat-plate beam-splitting photovoltaic thermal systems for building energy management applications

Analysis of coolant inlet/outlet layout and non-uniform cell spacing on thermal management of pouch battery packs

Solar-driven integrated device for simultaneous direct air capture and atmospheric water harvesting

Oblique-fn heat sink design for uniform CPU cooling in immersion-cooled servers

Liquid-state dipolarcaloric refrigeration cycle with nitrate based salts

Experimental Study on Falling Film Evaporation Heat Transfer of R-1233zd(E) on Horizontal Enhanced Tubes for High-Temperature Industrial Heat Pump Applications

Optimization of heat sinks for data center server CPUs cooled via single-phase immersion cooling

Performance characteristics of new enhanced heat transfer tubes for evaporator/absorber in absorption chiller

열 및 전기 에너지 동시 저장 이산화탄소 배터리 시스템

저온열원 구동 하이브리드 열에너지 및 전기에너지 관리 시스템

이중 층을 포함하는 철 산화물 복합체 및 이의 제조 방법

흡수식 에너지 저징 및 냉난방 동시활용 시스템

태양광 패널에 적용하기 위한 냉각 유닛 및 이의 용도

습기 제거를 위한 에멀션 타입의 제습용 조성물 및 그 제조 방법

가스 하이드레이트 치환 기반의 열교환 시스템

이산화탄소 포집을 위한 액체 흡착제 및 그 제조 방법

이산화탄소로 유도되는 고밀도 열에너지 발생 가능한 이산화탄소 흡수제

Hybrid Absorption Heat Pump System using Renewable Heat

Diffusion Absorption Refrigeration Apparatus and Refrigeration Method

피커링 에멀젼 상태로 제공되는 이산화탄소 화학적 흡수제를 이용한 이산화탄소 포집제 …

재생열원이용 하이브리드 흡수식 열펌프 시스템

Carbon Dioxide Photo-conversion Reactor

이산화탄소 광전환 반응기

냉동공조 실험장치

Yong Tae Kang

This study investigates the thermal conductivity and viscosity of copper nanoparticles in ethylene glycol. The nanofluid was prepared by synthesizing copper nanoparticles using a chemical reduction method, with water as the solvent, and then dispersing them in ethylene glycol using a sonicator. Volume loadings of up to 2% were prepared. The measured increase in thermal conductivity was twice the value predicted by the Maxwell effective medium theory. The increase in viscosity was about four times of that predicted by the Einstein law of viscosity. Analytical calculations suggest that this nanofluid would not be beneficial as a coolant in heat exchangers without changing the tube diameter. However, increasing the tube diameter to exploit the increased thermal conductivity of the nanofluid can lead to better thermal performance.

Enhanced thermal conductivity and viscosity of copper nanoparticles in ethylene glycol nanofluid

The convective instability driven by buoyancy and heat transfer characteristics of nanofluids are investigated analytically. This paper proposes a factor which describes the effect of nanoparticle addition on the convective instability and heat transfer characteristics of a base fluid. The Bruggeman model based on the mean field approach for expressing the thermal conductivity enhancement is chosen as a lower bound of the thermal conductivity relationship. The results show that as the density and heat capacity of nanoparticles increase and the thermal conductivity and the shape factor of nanoparticles decrease, the convective motion in a nanofluid sets in easily. The heat transfer coefficient of a nanofluid is enhanced by all parameters with respect to the volume fraction of nanoparticles.

Analysis of convective instability and heat transfer characteristics of nanofluids

The objectives of this paper are to examine the effect of nano particles on the bubble type absorption by experiment and to find the optimal conditions to design highly effective compact absorber for NH 3 /H 2 O absorption system. The initial concentrations of NH 3 /H 2 O solution and the kinds and the concentrations of nano particles are considered as key parameters. The results show that the addition of nano particles enhances the absorption performance up to 3.21 times. Moreover, the absorption rate increases with increasing concentration of nano particles and the nano particles are more effective for lower absorption potential solution. The potential enhancement mechanism for binary nanofluid is suggested. The experimental correlations of the effective absorption ratio for each nano particles, Cu, CuO, and Al 2 O 3 , are suggested within ±10% error-band.

The effect of nano-particles on the bubble absorption performance in a binary nanofluid

In this study, the methanol-based nanofluids with Al 2 O 3 and SiO 2 nanoparticles are prepared by dispersing nanoparticles in pure methanol using an ultrasonic equipment. The main objective of this paper is to measure the thermal conductivity of the methanol-based nanofluids. We have also measured the zeta potential, particle size and Tyndall effect for the present nanofluids. The transient hot-wire method is applied for measuring the thermal conductivity of methanol-based nanofluids. The measurement uncertainty in repeatability is obtained as 1.95% for deionized (DI) water and 1.34% for pure methanol, respectively. The effective thermal conductivity of methanol-based nanofluids is measured at a temperature of 293.15K. The results show that the thermal conductivity increases with an increase of the nanoparticle volume fraction, and the enhancement is observed to be 10.74% and 14.29% over the basefluid at …

Thermal conductivity measurement of methanol-based nanofluids with Al2O3 and SiO2 nanoparticles

Nanofluids produced by dispersing nanoparticles in the basefluid have been paid wide attention due to the reported superior thermophysical properties which probably lead to a strongly promising potential in application. Therefore, numerous studies have been carried out experimentally and theoretically to investigate the heat and mass transfer performance by using nanofluids in a number of fields in recent years. Some groups have reviewed the experimental results, mechanisms and models on the heat transfer enhancement of nanofluids, and most of them are concentrated on thermal conductivity. However, no comprehensive review article focuses on the mass transfer performance affected by the suspended nanoparticles in nanofluids. Thus in this study, a brief review of heat transfer characteristics in nanofluids has been performed at first, then we firstly take a critical review of the previous literature on mass …

Review on combined heat and mass transfer characteristics in nanofluids

In the present study, suspensions of Al 2 O 3 and SiO 2 nanoparticles in methanol (nanofluid) are produced and analyzed for the application of CO 2 absorption in a tray column absorber. The absorber is an acrylic tray column with twelve plates. The column is a sieve tray type which has flat perforated plates where the vapor velocity keeps the liquid from flowing down through the holes and the CO 2 gas and methanol liquid are brought in contact in a counter-current flow. The test section is equipped with two mass flow meters to measure the absorption rate. The results show maximum enhanced absorption rates of 9.4% and 9.7% for Al 2 O 3 and SiO 2 particles (compared to pure methanol), respectively. It is also found that SiO 2 nanoparticle is a better candidate than Al 2 O 3 nanoparticle and 0.05 vol% of nanoparticles is an optimum condition for CO 2 absorption enhancement for the present experimental conditions.

CO2 absorption enhancement by methanol-based Al2O3 and SiO2 nanofluids in a tray column absorber

The objectives of this paper are to visualize the bubble behavior during the NH 3 /H 2 O absorption process with chemical surfactant and nano-particles and to study the effect of nano-particles and surfactants on the absorption characteristics. Binary nanofluid which means binary mixture with nano-sized particles is tested to apply nanofluid to the absorption system. Cu, CuO and Al 2 O 3 nano-particles are added into NH 3 /H 2 O solution to make the binary nanofluids, and 2-ethyl-1-hexanol, n-octanol and 2-octanol are used as the surfactants. The concentration of ammonia in the basefluid, that of nano-particles in the nanofluid, and that of surfactants in the nanofluid are considered as the key parameters. The results show that the addition of surfactants and nano-particles improves the absorption performance up to 5.32 times. It can be concluded that the addition of both surfactants and nano-particles enhances …

Absorption performance enhancement by nano-particles and chemical surfactants in binary nanofluids

A latent heat storage nanocomposite made of stearic acid (SA) and multi-walled carbon nanotube (MWCNT) is prepared for thermal energy storage application. The thermal properties of the SA/MWCNT nanocomposite are characterized by SEM (scanning electron microscopy) and DSC (differential scanning calorimeter) analysis techniques, and the effects of different volume fractions of MWCNT on the heat transfer enhancement and thermal performance of stearic acid are investigated during the charging and discharging phases. The SEM analysis shows that the additive of MWCNT is uniformly distributed in the phase change material of stearic acid, and the DSC analysis reveals that the melting point of SA/MWCNT nanocomposite shifts to a lower temperature during the charging phase and the freezing point shifts to a higher temperature during the discharging phase when compared with the pure stearic acid …

Enhancement of heat transfer for thermal energy storage application using stearic acid nanocomposite with multi-walled carbon nanotubes

The objectives of this paper are to analyze a combined heat and mass transfer for an ammonia–water absorption process, and to carry out the parametric analysis to evaluate the effects of important variables such as heat and mass transfer areas on the absorption rate for two different absorption modes — falling film and bubble modes. A plate heat exchanger with an offset strip fin (OSF) in the coolant side was used to design the falling film and the bubble absorber. It was found that the local absorption rate of the bubble mode was always higher than that of the falling film model leading to about 48.7% smaller size of the heat exchanger than the falling film mode. For the falling film absorption mode, mass transfer resistance was dominant in the liquid flow while both heat and mass transfer resistances were considerable in the vapor flow. For the bubble absorption mode, mass transfer resistance was dominant in the …

Analytical investigation of two different absorption modes: falling film and bubble types

In thermal storage system, a high thermal conductivity of Phase Change Materials (PCM) is required to complement the crystallization phenomenon of the PCM during the discharging process. In this study, PCM with carbon additives, Multi-walled Carbon nanotube, Graphite and Graphene, are manufactured and the thermal conductivity of the PCM is measured by the transient hot-wire method for thermal storage application. The thermal conductivity of the PCM is enhanced by adding the carbon additives, and the effect of Poly Vinyl Pyrrolidone (PVP) as a dispersion stabilizer on the thermal conductivity is evaluated. It is found that the heat transfer rate enhances up to 3.35 times in the case of Graphite at 5.0 vol%. It is finally concluded that Graphite is the most promising candidate for heat transfer enhancement of stearic acid among three carbon additives even though Graphene gives the highest thermal conductivity …

Thermal conductivity and heat transfer performance enhancement of phase change materials (PCM) containing carbon additives for heat storage application

The objectives of this study are to measure the vapor absorption rate and heat transfer rate for falling film flow of binary nanofluids, and to compare the enhancement of heat transfer and mass transfer under the same conditions of nanofluids. The key parameters are the base fluid concentration of LiBr, the concentration of nanoparticles in weight %, and nanoparticle constituents. The binary nanofluids are H 2 O/LiBr solution with nanoparticles of Fe and Carbon nanotubes (CNT) with the concentrations of 0.0, 0.01 and 0.1wt %. The vapor absorption rate increases with increasing the solution mass flow rate and the concentration of Fe and CNT nanoparticles. It is found that the mass transfer enhancement is much more significant than the heat transfer enhancement in the binary nanofluids with Fe and CNT. It is also found that the mass transfer enhancement from the CNT nanoparticles becomes higher than that from …

Heat and mass transfer enhancement of binary nanofluids for H2O/LiBr falling film absorption process

An innovative dual-mode thermochemical sorption energy storage method is proposed for seasonal storage of solar thermal energy with little heat losses. During the charging phase in summer, solar thermal energy is stored in form of chemical bonds resulting from thermochemical decomposition process, which enables the stored energy to be kept several months at ambient temperature. During the discharging phase in winter, the stored thermal energy is released in the form of chemical reaction heat resulting from thermochemical synthesis process. Thermodynamic analysis showed that the advanced dual-mode thermochemical sorption energy storage is an effective method for the long-term seasonal storage of solar energy. A coefficient of performance (COP h ) of 0.6 and energy density higher than 1000 kJ/kg of salt can be attained from the proposed system. During the discharging phase at low ambient …

Performance analysis of an integrated energy storage and energy upgrade thermochemical solid–gas sorption system for seasonal storage of solar thermal energy

The objectives of this paper are to examine the effect of nanoparticles on the pool type absorption heat transfer enhancement and to find the optimal conditions to design a highly effective compact absorber for NH 3 /H 2 O absorption system. The binary nanofluids which mean binary mixture with nano-sized particles are tested to apply nanofluids to the absorption system. Al 2 O 3 and carbon nanotube (CNT) particles are added to make the binary nanofluids in the binary mixture of NH 3 /H 2 O. The effect of Al 2 O 3 nanoparticles and CNT on the absorption performance is studied experimentally. The experimental ranges of the key parameters are 20% of NH 3 concentration, 0–0.08vol% (volume fraction) of CNT particles, and 0–0.06vol% of Al 2 O 3 nanoparticles. For the NH 3 /H 2 O nanofluids, the heat transfer rate and absorption rate with 0.02vol% Al 2 O 3 nanoparticles were found to be 29% and 18% higher than those without …

The effects of nanoparticles on absorption heat and mass transfer performance in NH3/H2O binary nanofluids

Evaporation modes and kinetics of sessile droplets of water on micropillared superhydrophobic surfaces are experimentally investigated. The results show that a constant contact radius (CCR) mode and a constant contact angle (CCA) mode are two dominating evaporation modes during droplet evaporation on the superhydrophobic surfaces. With the decrease in the solid fraction of the superhydrophobic surfaces, the duration of a CCR mode is reduced and that of a CCA mode is increased. Compared to Rowan’s kinetic model, which is based on the vapor diffusion across the droplet boundary, the change in a contact angle in a CCR (pinned) mode shows a remarkable deviation, decreasing at a slower rate on the superhydrophobic surfaces with less-solid fractions. In a CCA (receding) mode, the change in a contact radius agrees well with the theoretical expectation, and the receding speed is slower on the …

Evaporation kinetics of sessile water droplets on micropillared superhydrophobic surfaces

Carbon dioxide hydrate has been paid growing attention due to its application potentials like being used as a secondary refrigerant and sequestration in the deep ocean. Therefore, there has been a lot of research on various gas hydrates, including methane hydrate, ethane hydrate, methane–CO 2 mixture hydrate and so on. However, there is no review especially on the CO 2 hydrate and its cooling application. In this paper, the review provides the comprehensive understanding of the CO 2 hydrate with focus on the formation and dissociation models, including the kinetic and thermodynamic ones, as well as its applications. It is proposed that more experimental and modeling work should be carried out on CO 2 hydrate dissociation, and the kinetic models should be developed by considering the effect of additives. It is also proposed that the cooling application of CO 2 hydrate will become popular in the very near …

Review on CO2 hydrate formation/dissociation and its cold energy application

This article presents a numerical investigation of the heat exchanger design effect on the performance of closed cycle, two-bed adsorption cooling systems with silica gel as adsorbent and water as refrigerant. It is well known that the shorter the cycle time, lower is the performance (cooling capacity and coefficient of performance). A long cycle time is responsible for lower cooling capacity. In this study, a non-dimensional switching frequency, which is inversely proportional to the cycle time, is defined and an optimum switching frequency is derived based on parametric analysis. The effect of other heat exchanger design parameters such as adsorbent number of transfer unit (NTU), bed Biot number (Bi), the heat exchanger aspect ratio (Ar) and the ratio of fluid channel radius to the adsorbent thickness (Hr), on the system performance has been investigated. The results show that the switching frequency ω , bed NTU, Ar …

Heat exchanger design effect on the system performance of silica gel adsorption refrigeration systems

The objective of this study is to propose and evaluate advanced absorption cycles for the coefficient of performance (COP) improvement and temperature lift enhancement applications. The characteristics of each cycle are assessed from the viewpoints of the ideal cycle COP and its applications. The advanced cycles for the COP improvement are categorized according to their heat recovery method: condensation heat recovery, absorption heat recovery, and condensation/absorption heat recovery. In H 2 O–LiBr systems, the number of effects and the number of stages can be improved by adding a third or a fourth component to the solution pairs. The performance of NH 3 –H 2 O systems can be improved by internal heat recovery due to their thermal characteristics such as temperature gliding. NH 3 –H 2 O cycles can be combined with adsorption cycles and power generation cycles for waste heat utilization, performance …

Review of advanced absorption cycles: performance improvement and temperature lift enhancement

The objectives of this paper are to develop a combined power generation cycle using refuse incineration and LNG cold energy, and to conduct parametric analysis to investigate the effects of key parameters on the thermal and exergy efficiencies. The combined cycle consists of an ammonia–water Rankine cycle with refuse incinerator and a LNG cold energy cycle. The combined cycle is compared with the conventional steam Rankine cycle. It was found that the thermal and the exergy efficiencies of the combined cycle were 1.53 and 1.43 times higher than those of the conventional cycle, respectively. The ammonia condensing temperature, turbine inlet and outlet pressures and overall conductance (UA) of the condenser are considered as the key parameters. The thermal and the exergy efficiencies increase with increasing the turbine inlet pressure. As the turbine outlet pressure increases, the thermal efficiency of …

A combined power cycle using refuse incineration and LNG cold energy

The development of advanced heat transfer fluids with enhanced thermal conductivity is essential to improve the effective heat transfer behavior of conventional coolants. Thermal conductivity enhancement has been reported for colloidal suspension formulated with different nanoparticles and recently also for water-in-oil emulsion. In the present study, the concept of emulsifying water in oil by means of non-ionic surfactant is employed and physical properties such as thermal conductivity and viscosity are investigated experimentally. Dynamic light scattering shows that the droplet size is dependent on the water concentration: the higher the water concentration, the larger the water droplet size. Based on thermal conductivity and viscosity measurements of nanoemulsions, their performance as cooling media is compared with the performance of pure oil through consideration of the pumping power required to achieve …

Thermal conductivity and viscosity of water-in-oil nanoemulsions

In this study, Al 2 O 3 nanoparticles and NaCl aqueous solution are combined into Al 2 O 3 /NaCl aqueous solution nanofluids to enhance the CO 2 absorption of the base fluid (NaCl aqueous solution). The absorption experiments are carried out in the bubble type absorber system. The particle concentration ranges from 0.005 to 0.1 vol%. It is found that the optimum concentration of Al 2 O 3 nanoparticles is 0.01 vol% in the NaCl aqueous solution-based nanofluids and then CO 2 solubility is enhanced to 11.0%, 12.5% and 8.7% for Al 2 O 3 /NaCl aqueous solution at 30 °C, 20 °C and 10 °C, respectively. It is concluded that the effect of nanoparticles on the mass transfer enhancement is more significant in the region of unsaturated state than that of the saturated state.

고려대 에너지물질순환연구실

교수님 소개

강용태

연구실 소개

연구실 키워드

알럼나이가 간 회사

연구실 지원 방법

대우 조건

연도별 논문 인용수

저널 & 학회 논문 출판 수

연구실 논문 목록

Self-assembled pellet adsorbents for sub-ambient direct air capture: from material structuring to system-level optimization

Low waste heat driven indoor CO2 capture via 3D-printed hybrid TPMS monoliths

Ammonia-based thermally regenerative batteries enable waste-heat-powered defrosting

연구실 보유 특허

대학별 입시끈

우리 연구실 모집

교수님 소개

강용태

연구실 키워드

알럼나이가 간 회사

연구실 지원 방법

대우 조건

연도별 논문 인용수

저널 & 학회 논문 출판 수

연구실 논문 목록

Self-assembled pellet adsorbents for sub-ambient direct air capture: from material structuring to system-level optimization

Low waste heat driven indoor CO2 capture via 3D-printed hybrid TPMS monoliths

Ammonia-based thermally regenerative batteries enable waste-heat-powered defrosting

연구실 보유 특허

최근 3년간 연구실적 높은 연구실

대학별 입시끈

우리 연구실 모집