• Title/Summary/Keyword: Constant temperature water bath

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Precision Control of Water Bath Temperature using Air Cooled Variable Refrigerant Flow Chiller (공랭식 변유량 냉매 냉동기를 적용한 수조 온도의 정밀 제어)

  • Jeong, Kwang-Ju;Kim, Young Il
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.14 no.4
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    • pp.27-34
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    • 2018
  • This study compared constant water bath performances of conventional water-cooled refrigerator and electric heater with an air-cooled VRF chiller and electric heater equipped with optimal control algorithm. In heating mode, the air cooled VRF chiller and electric heater combination reduced the set temperature arrival time by an average of 42 minutes, and energy was also reduced by 18%. In cooling mode, the two systems took 70 minutes to reach the set temperature and showed no difference. Energy was reduced by 33.5% with the new system. For constant temperature maintaining experiment, after reaching the set temperature of $15^{\circ}C$, $20^{\circ}C$ and $22^{\circ}C$, temperature deviations were all in the range of $-0.2^{\circ}C$ to $+0.1^{\circ}C$. Energy was reduced by an average of 84.9%. Through this study, possibility of precise temperature control by an air cooled VRF chiller system was confirmed.

Comparative analysis of strain according to the deposition of a constant temperature water bath of a denture-base artificial tooth produced using three-dimensional printing ultraviolet-curing resin (3D 프린팅용 광경화 수지를 사용하여 제작한 의치상용 인공치아의 항온수조 침적에 따른 변형률 비교 분석)

  • Kim, Dong-Yeon;Lee, Gwang-Young;Kim, Jae-Hong;Yang, Cheon-Seung
    • Journal of Technologic Dentistry
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    • v.42 no.3
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    • pp.202-207
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    • 2020
  • Purpose: This study is a comparative analysis of the strain according to deposition in a constant temperature water bath after manufacturing ultraviolet (UV)-cured artificial teeth. Methods: As a control group, 10 ready-made artificial teeth were selected as the first molar on the right side of the maxilla (RT group). Silicone was used as a duplicate of the artificial denture teeth. Experimental teeth were prepared in two groups using the prepared silicone mold. In the first experimental group, the UV-cured resin was injected into the negative silicone, followed by irradiation with a UV-curing machine for 5 minutes (5M group). In the second experimental group, the UV-cured resin was injected into the negative silicone, and then irradiated for 30 minutes using a UV-curing machine (30M group). The one-way ANOVA was performed, and post-test was analyzed by Tukey. Results: When immersed in a water bath for 15 days, it was found to be -0.3% in the RT group, -0.6% in the 5M group, and -0.7% in the 30M group. The results revealed -0.2% in the RT group, 0.2% in the 5M group, and -0.2% in the 30M group when they were in the bath for 30 days. Conclusion: In the water bath, the swelling was greater when deposited for 1 to 15 days, but was less when deposited for 15 to 30 days.

Difference between shrinkage rate of irradiation amount of 3D printing UV curable resin and shrinkage rate according to a constant temperature water bath (3D 프린팅용 UV 경화 수지의 조사량 및 항온수조 침적에 따른 수축률의 차이)

  • Kim, Dong-Yeon
    • Journal of Technologic Dentistry
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    • v.42 no.2
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    • pp.113-120
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    • 2020
  • Purpose: This study is to compare and analyze the shrinkage of the specimen after UV irradiation of UV cured resin at 5, 15, and 30 minutes. Methods: A cylindrical UV cured specimen was produced using a stainless steel mold. UV cured resin specimens were prepared in three groups: 5 minutes cured (5M), 15 minutes cured (15M), and 30 minutes cured (30M). The measurement was made in total 3rd. The measurement was made in total 3rd. The primary measurement was made after 24 hours using a digital measuring instrument. The 2nd and 3rd measurements were deposited in a constant temperature water bath and the shrinkage was measured. The measured data was calculated by referring to the ASTM C326 linear measurement calculation method. T-test and One-way ANOVA were performed to test the significance between groups. The post-test was conducted with Tukey (α=0.05). Results: When the inner diameter and the outer diameter of the three groups not placed in the water bath were compared and analyzed, the contraction was the smallest at 6.8% in the 5M group, and the contraction was the largest at 7.3% in the 30M group. In the outer diameter, the contraction of the 5M group was the smallest at 3.5%, and the contraction of the 30M group was the largest at 4.5%. Shrinkage decreased in all three groups immersed in a water bath for 3-7 days. Conclusion: In the UV cured resin specimen, the shrinkage increased as the amount of UV irradiation increased.

Comparative analysis of strain according to two wavelengths of light source and constant temperature bath deposition in ultraviolet-curing resin for dental three-dimensional printing (치과 3D 프린팅용 자외선 경화 레진에 광원의 두 가지 파장에 따른 경화 및 항온수조 침적에 따른 변형률의 비교 분석)

  • Kim, Dong-Yeon;Lee, Gwang-Young;Kang, Hoo-Won;Yang, Cheon-Seung
    • Journal of Technologic Dentistry
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    • v.42 no.3
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    • pp.208-212
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    • 2020
  • Purpose: This study aimed to analyze the shrinkage and expansion strain of ultraviolet (UV)-cured resin according to the wavelength of the light source and compare the shrinkage and expansion. Methods: We prepared the mold with according to the ISO 4049 specimen. The size of the circle in the mold was prepared with a height of 6.02 mm and a diameter of 4 mm. UV-curable resin for three-dimensional (3D) printing was injected into the circular mold. The control group was irradiated with a wavelength of 400~405 nm using UV-curing equipment (400 group), and the experimental group was irradiated with a wavelength of 460~465 nm (460 group). Both groups were produced ten specimens. The produced specimen was first measured with a digital micrometer. After the first measurement, the specimen was immersed in a constant temperature water bath for 15 days, after which the second measurement was performed, and the third measurement was taken after 30 days. The measured values were analyzed using the independent sample t-test (α=0.05). Results: In the non-immersion water tank, the contraction was 0.9% in the 400 group and 1.3% in the 460 group. In the constant temperature bath, the expansion was high at -0.4% in the 400 group for 15 days, and the smallest expansion was -0.03% for the 400 group for 30 days. There were significant differences between the two groups (p<0.05). Conclusion: The 400 group had a lower UV resin specimen strain than the 460 group. Therefore, it is recommended to use the wavelength required by the UV-curing resin.

Investigation of Standard Error Range of Non-Contact Thermometer by Environment (외부 환경 변화에 의한 비 접촉 체온계의 오차 범위 측정)

  • Kim, Jeongeun;Park, Sangwoong;Choi, Heakyung
    • Journal of The Korean Society of Integrative Medicine
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    • v.8 no.4
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    • pp.307-321
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    • 2020
  • Purpose : A person infected by SARS-CoV2 may present various symptoms such as fever, pain in lower respiratory tract, and pneumonia. Measuring body temperature is a simple method to screen patients. However, changes in the surrounding environment may cause errors in infrared measurement. Hence, a non-contact thermometer controls this error by setting a correction value, but it is difficult to correct it for all environments. Therefore, we investigate device error values according to changes in the surrounding environment (temperature and humidity) and propose guidelines for reliable patient detection. Methods : For this study, the temperature was measured using three types of non-contact thermometers. For accurate temperature measurement, we used a water bath kept at a constant temperature. During temperature measurement, we ensured that the temperature and humidity were maintained using a thermo-hygrometer. The conditions of the surrounding environment were changed by an air conditioner, humidifier, warmer, and dehumidifier. Results : The temperature of the water bath was measured using a non-contact thermometer kept at various distances ranging from 3~10 cm. The value measured by the non-contact thermometer was then verified using a mercury thermometer, and the difference between the measured temperatures was compared. It was observed that at normal surrounding temperature (24 ℃), there was no difference between the values when the non-contact thermometer was kept at 3 cm. However, as the distance of the non-contact thermometer was increased from the water bath, the recorded temperature was significantly different compared with that of mercury thermometer. Moreover, temperature measurements were conducted at different surrounding temperatures and the results obtained significantly varied from when the thermometer was kept at 3 cm. Additionally, it was observed that the effect on temperature decreases with an increase in humidity Conclusion : In conclusion, non-contact thermometers are lower in lower temperature and dry weather in winter.

Experimental Study on Heat Transfer and Pressure Drop of Heat Exchangers for Cooling Fan Coil Unit (냉방용 팬코일 유닛 열교환기의 열전달 및 압력강하 특성 실험연구)

  • Kwon, Young-Chul;Ko, Kuk-Won;Kwon, Jeong-Tae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.9 no.3
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    • pp.599-604
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    • 2008
  • An experimental study has been performed to investigate the air-side capacity and pressure drop of the fin-tube heat exchanger for a fan coil unit under a cooling condition. The experimental data of five kinds of slit fin-tube heat exchangers were measured using an air-enthalpy calorimeter and a constant temperature water bath. Cooling capacities at the air and water rating flow rates were larger at the lower inlet water temperature. With increasing the water flow rate, the cooling capacity increased at the constant rate. Under the lower inlet water temperature, since the condensate was generated more on the fin-tube surface, the air-side pressure drop of the heat exchanger was larger.

A Basic Study of the Snow Melting System for the Anti-Freezing Road using the Pulsating Heat Pipe (PHP를 이용한 도로융설 시스템에 관한 기초연구)

  • Kim, J.S.;Ha, S.J.;Son, K.J.
    • Journal of Power System Engineering
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    • v.14 no.3
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    • pp.19-24
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    • 2010
  • The purpose of this study is to develop a snow melting system using the pulsating heat pipe(PHP). The experimental apparatus is consisted of a PHP, a concrete structure, a constant water thermostatic bath and a flowmeter. The experiment was performed at the outdoor air temperature of $-8^{\circ}C$ and inlet temperature of hot water of $75^{\circ}C$. PHP is the closed and non-loop type heat exchanger which is charging R-410A as an operating fluid. As experimental results, the temperature profile of vertical and horizontal orientation of concrete structure was measured with operating time. The heat flux of the snow melting was required more than 300 $W/m^2$. We confirmed that the snow melting system using the PHP was useful for anti-freezing road.

Estimation of the thermal performance on the double slab floor with supplying air (급기가 되는 이중바닥 구조체의 열 성능 평가)

  • Cha, Kwang-Seok;Park, Myung-Sig;Lee, Dae-Woo;Nam, Woo-Dong
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.866-871
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    • 2006
  • Recently according to the fashion of well-being, the case study of under floor heating system type for residential space is increasing. Specially double slab floor system can make several roles as reducing the acoustic noises and also supplying fresh air through the gap. So in present study floor heating performance was examined with various location of the space in the case of floor supply air and ceiling supply air. In both cases return air went out through ceiling opening. As one of the result is that when using the heat pipe type floor heating system the temperature difference between supply and return water was $15.2^{\circ}C$, but in case of commercial type floor heating system the temperature difference was $5.3^{\circ}C$ when the supply water temperature was $50^{\circ}C$.

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Experimental Study on Heating Performance Characteristics of Air Source Heat Pump with Air to Water Type (공기열원 히트펌프의 난방 성능특성에 관한 실험적 연구)

  • Lee, Kwon-Jae;Kwon, Young-Chul;Chun, Chong-Keun;Park, Sam-Jin;Kwon, Jeong-Tae;Huh, Cheol
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.23 no.6
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    • pp.400-405
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    • 2011
  • This paper presents the heating performance characteristics of the air source heat pump with air to water type. The heating capacity, COP, P-h diagram were measured at various operating conditions, air-side temperatures, relative humidities, and inlet/outlet water temperature under the standard heating condition of KS B 6275. The experimental data for the heat pump were measured using the air-enthalpy calorimeter and the constant temperature water bath. As the air-side temperature increases, the heating capacity and COP increase. The effect of the air-side relative humidities on the heat pump performance is insignificant. The heat pump performance on inlet and outlet water temperatures and air-side temperatures(-7, -11, $-15^{\circ}C$) were studied. Heating capacity and COP increased about 27~39% with the air-side temperature increasing. Enthalpy between the front and the rear of condenser decreased about 6% by increasing of the inlet water temperature. These results can be utilized in the design of the air source heat pump system with air to water type.

The Study on the Structure and Performance of Heat Pump Calorimeter (열펌프 열량계 구조 및 성능 특성 연구)

  • Park, Seung Byung;Lee, Sang-Hyeok;Choi, Jinnil;Choi, Jong Min
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.11 no.4
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    • pp.7-13
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    • 2015
  • The efficiency, reliability and performance of any heat pump unit can only be ascertained after it has been tested and rated. For this reason, specific facilities, equiped with testing plants are built. Heat pump calorimeter is the facilities used by most of these testing facilities in their rating and certification process. The ultimate function of calorimeters is to, control and maintain the constant standard test conditions (indoor/outdoor entering temperatures and flow rate etc) during testing period. In this study, the test standards of heat pump unit and the structure of the calorimeter are surveyed. In addition, this study analyzes the total energy consumption of a water to water heat pump calorimeter. Heat pump calorimeter consumed much energy to excute the heat pump tests. The energy consumption of the calorimeter was higher than the heat pump unit, and it was increased as the heat pump unit capacity decreased.