• Title/Summary/Keyword: Indoor Air Temperature

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Analytical Study of Cooling Performance Comparison in a Refrigerator Truck Using R404A and R744 (R404A와 R744의 냉매를 이용한 냉동탑차 냉장성능 비교에 관한 해석적 연구)

  • Myung, Chi-Wook;Kim, Sang-Hun;Cho, Hong-Hyun
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.6
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    • pp.119-125
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    • 2011
  • The analysis of performance characteristics in a refrigerator truck using R404A and R744 was carried out by using theoretical method, and each performance was compared with a variation of operating conditions. The components and cycle simulation model were developed by using EES program. To investigate the performance characteristics with operating conditions, the performance of both systems was simulated according to indoor temperature, outdoor temperature, outdoor air velocity and compressor speed. As a result, the R744 system had a better COP than R404A system for given operating condition. The cooling capacity was not increased over the outdoor air velocity of 3 m/s. Besides, the performance of R404A system was more sensitive to operating conditions compared to that of R744 system.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 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.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. 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 fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are 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 general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, 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 is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

Stabilizing Soil Moisture and Indoor Air Quality Purification in a Wall-typed Botanical Biofiltration System Controlled by Humidifying Cycle (가습 주기에 따른 벽면형 식물바이오필터의 토양 수분 안정화 및 실내공기질 정화)

  • Lee, Chang Hee;Choi, Bom;Chun, Man Young
    • Horticultural Science & Technology
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    • v.33 no.4
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    • pp.605-617
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    • 2015
  • The ultimate goal of this research is to develop a botanical biofiltration system that combines a green interior, biofiltering, and automatic irrigation to purify indoor air pollutants according to indoor space and the size of biofilter. This study was performed to compare the stability of air flow characteristics and removal efficiency (RE) of fine dust within a wall-typed (vertical) botanical biofilter depending on humidifying cycle and to investigate RE of volatile organic compounds (VOCs) by the biofilter. The biofilter used in this experiment was designed as an integral form of water metering pump, water tank, blower, humidifier, and multi-level planting space in order to be suitable for indoor space utilization. As a result, relative humidity, air temperature, and soil moisture content (SMC) within the biofilter showed stable values regardless of three different humidifying cycles operated by the metering pump. In particular, SMCs were consistently maintained in the range of 27.1-29.7% during all humidifying cycles; moreover, a humidifying cycle of operating for 15 min and pausing for 45 min showed the best horizontal linear regression (y = 0.0008x + 29.09) on SMC ($29.0{\pm}0.2%$) during 120 hour. REs for number of fine dust (PM10) and ultra-fine dust (PM2.5) particles passed through the biofilter were in the range of 82.7-89.7% and 65.4-73.0%, respectively. RE for weight of PM10 passed through the biofilter was in the range of 58.1-78.9%, depending on humidifying cycle. REs of xylene, ethyl benzene, total VOCs (TVOCs), and toluene passed through the biofilter were in the range of 71.3-75.5%, while REs of benzene and formaldehyde (HCHO) passed through the biofilter were 39.7% and 44.9%, respectively. Hence, it was confirmed that the wall-typed botanical biofilter suitable for indoor plants was very effective for indoor air purification.

Development and Evaluation of Functional Lab Gowns in Point of Thermoregulation and Thermal Comfort (기능성 실험 가운의 개발 및 평가 -체온조절 및 온열 쾌적성을 중심으로-)

  • 최정화;이주영;김소영
    • Journal of the Korean Society of Clothing and Textiles
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    • v.28 no.2
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    • pp.292-302
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    • 2004
  • The purpose of this study was to evaluate thermal properties of lab gowns developed from the point of safety and work efficiency. We evaluated thermal and subjective responses of subjects wearing functional new lab gowns (Type B, C, D) and a popular lab gown on the market (Type A). Type B was a new lab gown made of woven fabric with functional cuffs. Type C was a new apron made of woven fabric with arm protectors. Type D was a new lab gown made of non-woven material with functional cuffs and openings around the armpits. Temperature in the climatic chamber was set at 19$^{\circ}$C as an indoor temperature in winter and at 24$^{\circ}$C in summer. There were no significant differences in rectal temperature and heart rate among four types of gowns and between two air temperatures for 120 min. Mean skin temperature was much higher in the type A and B than in He type C and D (p .05). In the 19$^{\circ}$C air, clothing microclimate temperature on the back was the highest in the type B and was the lowest in the type C (p .05). Clothing microclimate humidity was not significant differences among gowns. In subjective .esponses, subjects perceived that Type B was the warmest gown in the 19$^{\circ}$C and the hottest and more humid in the 24$^{\circ}$C than other gowns. Inversely, type C was the coolest gown among four gowns. Both in the 19$^{\circ}$C and in the 24$^{\circ}$C, the Type D had gained most responses of being comfortable. In conclusion, the temperature difference of 5$^{\circ}$C was more of an influencing factor than the difference from four types of lab gowns. Secondly, we recommend the manufacturers to make lab gowns with functional cuffs for safety purposes. Thirdly, the spread of the type of apron with arm protector will contribute to increase of the frequency of wearing in summer. Fourthly, it is necessary to study continuously about lab gowns with non-woven materials for researchers exposed to toxic chemical and biological materials.

A Study on the Peak Separation of Acetone and Acrolein Based on High-Performance Liquid Chromatography (HPLC) Method

  • Kim, Shin-Do;Kim, Chang-Hwan;Park, Jin-Su;Lee, Jeong-Joo
    • Bulletin of the Korean Chemical Society
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    • v.30 no.9
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    • pp.2011-2016
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    • 2009
  • To resolve the differentiation problem of acetone and acrolein in the analysis of carbonyls by high-performance liquid chromatography (HPLC), we investigated the optimum analytical conditions for their separation. Carbonyl compounds were collected by 2,4-dinitrophenylhydrazine (DNPH)-coated cartridges. We examined the influence of three experimental variables: temperature (25, 30, 40, 50 and 60 ${^{\circ}C}$), flow rate (1.0 and 1.2 mL/min), and relative mobile phase composition (among acetonitrile, water and tetrahydrofuran). The experimental results revealed the optimum analytical condition of a flow rate of 1.2 mL/min, temperature of 32 ${^{\circ}C}$ and mobile phase composition of acetonitrile: water: tetrahydrofuran = 34 : 52.8 : 13.2. The analysis of indoor air composition indicated that acrolein and acetone comprised 11% and 42% of all aldehydes, respectively.

Fabrication and Characteristics of Hot-film Anemometer (열박막 풍속계의 제작 및 특성)

  • Kim, Hyung-Pyo;Cho, Chan-Seob
    • Journal of Sensor Science and Technology
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    • v.9 no.3
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    • pp.190-195
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    • 2000
  • The paper presents the constant temperature digital hot-film anemometer that measures easily a wind velocity at the indoor. The output is linearized using microprocessor and analog-to-digital converter, because the fourth root of the wind velocity is the output voltage of the sensor. The comparison result between fabricated and reference anemometer is less than ${\pm}2%$. In the range of air temperature of $23^{\circ}C{\sim}60^{\circ}C$, the error is about ${\pm}1%$ in wind velocity 10m/sec.

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Development of Thermal Properties on the Roof Waterproof with Insulation System using the Diffused Reflection Material (확산반사를 이용한 경질시트 옥상 단열방수공법의 열성능 개선에 관한 연구)

  • Koo, Jae-Oh
    • KIEAE Journal
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    • v.7 no.1
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    • pp.73-80
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    • 2007
  • This paper aims to develop the diffused reflection material in order to reduce the solar absorption coefficient, and to compare the thermal properties with the different roof structure system; one is using the diffused reflection material applied the upper side of the rigid sheet waterproof system and the other is using the conventional up-side down waterproof system on the roof. For this purpose two experimental test boxes were made of same iso-panel wall and floor with different roof system. The experiment was carried out under these process; measure the surface temperature exposed solar radiation of the variation of the reflection materials(cement paste, silica, galvanized steel and titanium dioxide(TiO2)), measure and analyze the variation of the temperature distribution of the each roof system and indoor air in order to evaluate the thermal properties according to the different roof system. The result shows clearly that using the titanium dioxide(TiO2) might be more effective to reduce the solar insolation.

Application Study of the Predictive Pulse Control for Floor Heating System (바닥난방을 위한 부하 예측식 펄스제어 방식의 적용성 연구)

  • Cho, Sung-Hwan;Kim, Seong-Su;Kim, Yong-Bong;Na, Hee-Hyeong
    • Proceedings of the SAREK Conference
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    • 2007.11a
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    • pp.167-175
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    • 2007
  • A predictive pulse control strategy as a means of improving the energy efficiency of radiant floor heating systems is explored. Experiments at the apartment with floor heating system are conducted to assess and compare the energy performance of the predictive pulse control strategy with an existing conventional control strategy. The Results showed that new suggested PPCM( Predictive Pulse Control Method) was available to decrease the gap of $1{\sim}1.5^{\circ}C$ between maximum and minimum indoor temperature of each rooms. Therefore PPCM method was favor to radiant floor heating system which have a delay time of 10-20 minutes for heat transfer by floor layers.

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A Proposal for the Future of Summer in the Dosshouse (쪽방촌의 여름철 더위해결을 위한 방안 제시)

  • You, Nam Gyu;Kim, Min Sung;Kim, Bong Joo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2019.11a
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    • pp.102-103
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    • 2019
  • There are about 3,500 people living in the Seoul Dosshouse, including Namdaemun, Dongdaemun, Donui-dong, Changshin-dong, and Yeongdeungpo. The daytime temperature in the Dosshouse is 43 degrees and the indoor temperature is 35 degrees, which is also higher than the surrouding area. Most of them live in one-person the poor strata, where they have been fighting the heat and the summer. The old building is closely located and a 1.5-pyeong room without windows is a hot environment. Water, air-conditioning is difficult or impossible for people who are economically inferior and cannot solve their own solutions. The solution that can be provided by the country is to heat up once or twice a day by fire hose or shelter. However, there are many patients with discomfort, the distance is far, and the effect is insignificant. Therefore, through this experiment by using discarded banner, I would like to suggest a way to solve the summere heat of the Dosshouse.

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Thermal Performance of an Enthalpy Exchanger Made of Paper at Different Outdoor Temperatures and Humidities (외기 온·습도 변화에 따른 종이재질 전열교환 엘리먼트 성능에 관한 연구)

  • Kim, Nae-Hyun;Lee, Eul-Jong;Song, Kil-Sup;Oh, Wang-Kyu
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.7
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    • pp.697-702
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    • 2010
  • An enthalpy exchanger in which heat and moisture transfer occur between the indoor and outdoor air operates at various outdoor conditions. In this study, the effect of the outdoor-air temperature and humidity on the performance of an enthalpy exchanger was experimentally investigated. An apparatus was specially-made to accurately measure the incoming and outgoing dry- and wet-bulb air temperatures as well as the flow rates. Tests were conducted in constant-temperature and constant-humidity chambers at different outdoor temperatures and humidities. It is shown that the effectiveness of latent-heat exchange increases as the relative humidity increases; further, this effect exhibited minimal dependence on the absolute humidity. However, the effectiveness of sensible-heat exchange is independent of both temperature and humidity