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Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

A numerical study on the characteristics of the smoke movement and the effects of structure in road tunnel fire (도로터널 화재시 연기의 전파특성과 구조체에 미치는 영향에 관한 수치 해석적 연구)

  • Yoo, Ji-Oh;Oh, Byung-Chil;Kim, Hyo-Gyu
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.15 no.3
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    • pp.289-300
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    • 2013
  • This study numerically considered the characteristic of smoke movement and the effect of hot smoke gas on tunnel wall surface temperature during road tunnel fire under boundary condition of fire growth curve that is applied to fire analysis in road tunnels. The maximum heat release rate were 20 MW and 100 MW and tunnel air velocities were 2.5 m/s and velocity induced by thermal buoyancy respectively, also the cooling effect of tunnel wall was considered. As results, when tunnel air velocity was constant at 2.5 m/s during tunnel fire, due to the cooling effect of tunnel wall, the smoke layer was rapidly descent after some distance and it flowed the same patterns at the downstream. When heat release rate was 100 MW (and jet fan was not installed), the maximum temperature of tunnel wall surface has risen up to $615^{\circ}C$. The heat transfer coefficient of tunnel wall surface was varied from 13 to $23W/m^2^{\circ}C$ approximately.

Study on the energy-saving constant temperature and humidity machine operating characteristics (에너지 절감형 항온항습기 운전 특성에 관한 연구)

  • Cha, Insu;Ha, Minho;Jung, Gyeonghwan
    • Journal of Energy Engineering
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    • v.25 no.3
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    • pp.27-33
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    • 2016
  • The heat recovery system that was applied in this study, is the energy-saving type that can produce the maximum cooling capacity less power in use. In order to have a more precise control function the temperature and humidity of the constant temperature and humidity machine, control algorithm is applied to designed a fuzzy PID controller, and the outside air compensation device (air-cooled) demonstrated excellent ability to dehumidify the moisture, $-20^{\circ}C$ in winter. High efficiency and the low-noise type sirocco fan operate quitely and designed to fit the bottom-up and top-down in accordance with the characteristics of equipment. as a result of experiment data, the conversion efficiency is 95% or more, power recovery time is within 5sec, stop delay time is within 30sec, pump down time is 10sec, pump delay time is 5sec, heating delay time is 5sec, temperature deviation is ${\pm}2^{\circ}C$ (cooling deviation: $2^{\circ}C$, Heating deviation : $2^{\circ}C$), humidity deviation is a ${\pm}5%$ (humidification deviation 3.0%, dehumidification deviation 3.0%). Recently, ubiquitous technology is important. so, the constant temperature and humidity machine designed to be able to remotely control to via the mobile phone, and more scalable to support MMI software and automatic interface. Further, the life of the parts and equipment is extended by the failure.

A Study of Columnar Joint in Goheung, Jeollanam-do, Korea (전라남도 고흥지역에 분포하는 주상절리에 관한 연구)

  • Son, Jeong-Mo;Ahn, Kun Sang
    • Journal of the Korean earth science society
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    • v.37 no.6
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    • pp.332-345
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    • 2016
  • The columnar joints in Goheung are developed in three places of Yuju-san area, Palyeong-san and Yongbawi area. Vertical and fan-shaped columnar joints which have maximum width 100 m and maximum heigh 50 m are developed in the Yuju-san area Columnar joints are developed next to the road near the the Yuju-san and along the coast of Jijuk-do. Thick columnar joints of maximum width 1m are developed in the Paryeong-san area. Horizontal columnar joints of maximum width 50 cm at length of polygon side are developed on dyke in the Yongbawi area. The columnar joints show high rate of rectangles and pentagons in the number of polygons. The length of polygon side of columnar joints in study area ranges from 10 to 100 cm, and 20 cm among the range appears in high frequency. Columnar joints are developed vertically to the ground from the cooling surface in Yuju-san and Palyeong-san area. Columnar joints in Yongbawi area are developed vertically to the contact of country rocks. As a result, the columnar joints began cooling from the country rock contact. And columnar joints are developed vertically to contact surface. The rocks in columnar joints is rhyolitic welded tuff in Yuju-san and Palyeong-san area, dacite in Yongbawi area. In the acid volcanic rocks flow structure well developed. The white phenocryst mineral about 2 mm size by eye, is usually feldspar, and includes some quartz. The rate of $SiO_2$ is 70wt.% or more. It is the last stage of differentiation to calc-alkaline series. The columnar joints of the Yuju-san area are expected to be distributed along a band that extends to about 1km east of the stone pit.

The ETCS Convergence Terminal for Eco-driving and Vehicle Diagnostics (에코-드라이빙과 차량 진단 겸용 ETCS 융합 단말기)

  • Kim, Sam-Taek
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.12 no.2
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    • pp.29-34
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    • 2012
  • Nowadays, the problem of ETCS terminal in becoming popular gradually is that there is no services except for ETC. Therefore, we need new system that provide many type of additional services at one-terminal. In this paper, we study the additory function of ETCS terminal to afford many type of the vehicle administration beside collection and provider of traffic information. We descrived the method of Eco-driving function beside to save fuel signing instant and mean fuel-efficiency, measurement of section fuel-efficiency on OLED and then brings out the best driving habit in people and to prevent dangerous at the wheel as diagnosing engine oil, cooling water, fan belt, the point of changing consumables, diagnoses to an overheated engine, charges on generator through ECU. The multi-services terminal consist of the vehicle diagnosis module base on OBD-II and ETCS terminal.

Development Cooling and Dehumidifying System for Greenhouse using Hygroscopic properties of Lithium Bromide Solution (리튬브로마이드 수용액의 흡습성질을 이용한 온실 냉방 및 제습 시스템 개발)

  • Cho, La Hoon;Oh, Kwang Cheol;Lee, Sang Yeol;Joo, Sang Yeon;Park, Sun Yong;Lee, Seo Hyeon;Jeong, In Seon;Lee, Chung Geon;Kim, Dae Hyun
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 2017.04a
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    • pp.79-79
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    • 2017
  • 국내 여름철의 고온다습한 기후환경으로 인하여 온실 내부의 냉방 및 제습이 필수적인데, 온실 냉방 방식 중 증발냉각 시스템이 가장 효율이 높다고 알려져 있다. 하지만 증발냉각 시스템은 건조한 기후 지역에서 발달한 방식으로, 작물의 증산작용으로 인한 온실 내부 습도 상승에 따른 문제점이 발생되어 다습한 여름철 국내 기후에는 반드시 냉각과 제습이 동시에 필요하다. 따라서 증발냉각 방식 중 Fan and Pad 방식과 리튬브로마이드 수용액을 이용한 온실 냉방 및 제습을 위한 복합시스템에 관한 연구가 진행중이다. 현재 리튬브로마이드 수용액 제습 시 발생되는 발열량과 수용액의 무게변화와 같은 수용액의 흡습성질 대한 정확한 지표가 나타나 있지 않다. 이에 연구를 진행하기에 앞서 리튬브로마이드 흡습성질에 관한 데이터 자료가 필요하다고 판단되어 기초실험을 진행하였고, 본 연구에서는 Pilot Scale의 재생 순환시스템을 통해 리튬브로마이드 수용액의 흡습성질을 이용한 재사용 방안을 제시하였고, 시스템 내에서 외부투입공기와 작동유체의 흡습성질에 의한 반응 전후 온도변화 예측 모델을 수립하였다. 따라서 본 연구를 통해 리튬브로마이드 수용액의 흡습성질을 분석하고, 이를 이 용한 재생 순환 시스템에 관한 연구를 진행할 예정이다.

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Performance Evaluation Study of Solarwall-Photovoltaic Module to Generate Solar Electric Power (SWPV 태양 열-전기 복합생산 모듈 성능평가 연구)

  • Naveed Ahmed T;Kang E. C.;Lee E. J.
    • 한국신재생에너지학회:학술대회논문집
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    • 2005.06a
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    • pp.397-402
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    • 2005
  • Photovoltaic (PV) module can generate electricity using sunlight without causing any environmental degradation. Due to higher fossil fuel prices and environmental awareness, PV applications are becoming more popular as clean source of electricity generation. PV output is sensitive to the operating temperature and can be drastically affected in Building Integrated PV (BIPV) systems. PV Solarwall (SWPV) combination and PV systems have been evaluated in this study for improvement in electrical output and system costs. PV modules under forced ventilation. A 75W polycrystalline silicon PV module was fixed on SW in front of the ventilation fan as it was indicated to be the coolest position on the SW in phoenix simulations. The effectiveness of cooling by means of the forced ventilating air stream has been studied experimentally. The results indicate that there appears to be significant difference in temperature as well as electricity output comparing the SWPV and BIPV options. Electrical output power recovered is about $4\%$ during the typical day of the month of February. RETScreen(R) analysis of a 3kW PV system hypothetically located at Taegu has shown that with typical temperature reduction of $15^{{\circ}C$, it is possible to reduce the simple payback periods by one year. The work described in this paper may be viewed as an appraisal of a SWPV system based on its improved electrical and financial performances due to its ability to operate at relatively lower temperatures.

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Improving Fuel Efficiency of a Hybrid Excavator (하이브리드 굴삭기 연비 개선 연구)

  • Cho, Sungwoo;Yoo, Seungjin;Park, Cheol-Gyu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.2
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    • pp.211-217
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    • 2015
  • Emission gas regulations and constantly increasing fuel costs call for the worldwide use of environmentally friendly and energy-efficient machines in industry. To meet these requirements, a hybrid excavator prototype has been developed that incorporates an electric swing motor, engine assist motor, and ultra-capacitor module into a conventional hydraulic excavator of the 22-ton class. This paper mainly describes a few techniques to optimize its energy efficiency. These include 1) controlling the engine speed in proportion to the load torque, 2) controlling the pump displacement when driving the electric swing system, 3) managing the ultra-capacitor voltage to minimize the electrical energy loss, and 4) reducing the cooling fan speed to improve the energy efficiency of the system.

Study Growth Environmental Monitoring and Controlling Platform for Hydroponic (양액재배를 위한 생육환경 모니터링 및 제어 플랫폼에 관한 연구)

  • Yeon, In-won;Lee, Won-cheol
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.9
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    • pp.1132-1140
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    • 2016
  • According to global trend, despite the overall scale of agricultural industry has been downsized, agriculture accommodating cutting-edge ICT technologies has been proliferated, and various timely-issued relevant researches have been on progress to deploy the future food cultivation. In this paper, we propose an effective nutrient management system with web-based monitoring with functionality of controlling temperature, humidity, pH (hydrogen ion), EC (Electric Conductivity), LED and cooling fan to maintain the hydroponic nurturing environment being optimal. In this paper, in order the arduino hardware and java software are employed to control the nurturing environment automatically in optimal fashion. In proposed system, due to the usage of WiFi router with the socket communication and DB-assisted Web server with proper interfaces, it allows to facilitate the management to keep monitoring and controling overall hydroponic nurturing environment. Since the proposed Web-based management system provides the superior reliability, the short nurturing period and the robustness to the pest by controlling LED emitting color rather than conventional system, so it can be applied and appropriate for in-house vegetable factory overcoming limitation of time and location.

Fabrication of 365 nm Wavelength High Transmittance Silicone Resin TIR Lens and High Directivity Light Source Module for Exposure System (365 nm 파장대역 고투과율 실리콘 수지 TIR 렌즈 및 고지향성 노광기 광원모듈 제작)

  • Sung, Jun Ho;Yu, Soon Jae;Anil, Kawan;Jung, Mee Suk
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.31 no.4
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    • pp.267-271
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    • 2018
  • A high directivity TIR (total internal reflection) lens in the UV-A region was designed using a silicone resin, and a UV light source module with a maximum irradiation density of $150mW/cm^2$ was fabricated. The beam angle of the TIR lens was designed to be $8.04^{\circ}$ and the maximum diameter of the TIR lens was Ø13.5. A silicone resin having a UV transmittance of 93% and a refractive index of 1.4 at a wavelength of 365 nm was used, and the lens was manufactured using an aluminum mold, from which silicone could be easily released. The module was fabricated in a metal printed circuit board of COB (chip on board) type using a $0.75{\times}0.75mm^2$ UV chip. A jig was used to adjust the focal length between lens and chip and to fix the position of the lens. The optical characteristics such as illumination distributions of the lens and module were designed using 'LightTools' optical simulation software. The heat dissipation system was designed to use a forced-air cooling method using a heat-sink and fan.