• Title/Summary/Keyword: Superheat Temperature

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The EEV Control of the Multi-type Air-conditioning System by using a Fuzzy Logic Superheat Temperature Setpoint Reset Algorithm (퍼지로직 과열도 재설정 알고리즘을 사용한 멀티형 냉방시스템의 전자팽창밸브 제어)

  • 한도영;이상원
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.5
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    • pp.382-388
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    • 2003
  • Refrigerant flow rates of the multi-type air-conditioning system can be regulated by electronic expansion valves (EEV). The performance of the multi-type air-conditioning system may be improved by lowering the superheat at the compressor suction side. In this study, a superheat temperature setpoint reset algorithm was developed by using fuzzy logics, and a PI algorithm was applied to control the superheat temperature near setpoints. Experimental results showed energy savings and stable operations at a multi-type air-conditioning system. Therefore, the developed setpoint reset algorithm may be effectively used for the EEV superheat temperature control of the multi-type air-conditioning system.

A Study on Dynamic Characteristics of a Refrigeration System by Controlling the Evaporator Superheat (증발기 과열도제어에 따른 냉동장치의 동특성에 관한 연구)

  • 김재돌;오후규;윤정인
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.8
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    • pp.2012-2021
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    • 1995
  • An experimental study was performed for the analysis of dynamic characteristics of refrigeration system by controlling the evaporator superheat. Experimental data have been taken utilizing two different devices, thermostatic expansion valve(T.E.V.) and electronic expansion valve(E.E.V.), for the control of the evaporator superheat. The ranges of parameters, such as superheat, mass flow rate of refrigerant and inlet temperature of evaporator were 5-30.deg. C 90-170 kg/h and 10-25.deg. C, respectively. The data taken from the T.E.v.and E.E.v.were discussed with the control of the superheat, pressure drop, refrigerating capacity, compression work, evaporating temperature, condensing temperature and COP affecting performance characteristics of refrigeration system. In case of the refrigerant flow control with T.E..V., the superheat and pressure drop of the evaporator varied periodically, but the control with E.E.V., the parameters were very stable. In E.E.v.control, refrigerating capacity, compression work and evaporating temperature were decreased with increasing superheat, and the highest COP was obtained in the range of superheat from 5.deg. C to 15.deg. C.

The Study on Performance Characteristics due to the Superheat Temperature of $NH_3$ Refrigeration System (과열도 변화에 의한 $NH_3$ 냉동장치의 성능특성 연구)

  • Jeong, Sang-Sin;Kwon, Il-Wook;Ha, Ok-Nam
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1334-1339
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    • 2004
  • Nowadays CFCs and HCFCs refrigerants are restricted because it cause depletion of ozone layer. Accordingly, this experiment apply the $NH_3$ gas and not CFCs and HCFCs for refrigerant to study the performance characteristic from the superheat control and improve the energy efficiency from the high performance. The condensing pressure of refrigeration system is increased from 14.5bar to 16bar by 0.5bar and superheat temperature is increased from $0^{\circ}C$ to $10^{\circ}C$ by $1^{\circ}C$ at each condensing pressure. As the result of experiment, when the superheat temperature is $1^{\circ}C$ at each condensing pressure, the refrigeration system has the high performance.

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Transient fluid temperature fluctuation in boiling (푸울 沸騰時 過渡的 流體溫度 變動)

  • 김종일;정충식
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.1
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    • pp.44-47
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    • 1988
  • The present experiments of transient temperature variation and temperature fluctuation were conducted by bead type thermistors in pool boiling without a heat surface. The experimentally obtained conclusion were as follows. (1) The high transient temperature Variatian of 11.64.deg. C for a duration of 0.08 sec and a temperature freguency having a duration of 5.6*10$^{-2}$ sec in a flashing were measured. (2) The highest variation of transient temperature was shown at saturated temperature of 80.deg. C and superheat of 7.9.deg. C. (3) Temperature frequency was found to increase with superheat below 60.deg. C of saturated temperature, but above 60.deg. C it was relative to lower superheat and was found to decrease with higher superheat..

Expansion Valves Characteristics for Development of Control System on Air Conditioning and Refrigeration Systems (공조.냉동장치의 제어시스템 개발을 위한 팽창밸브 특성)

  • Kim, J.D.;Jang, J.E.;Yoon, J.I.
    • Journal of Power System Engineering
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    • v.2 no.3
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    • pp.34-40
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    • 1998
  • Performance characteristics of a refrigeration systems with various expansion valves and superheat changes were investigated experimentally. Experimental data have been taken utilizing three different devices; a thermostatic expansion valve, a linear type electronic expansion valve and a solenoid type electronic expansion valve. The data taken from tile three types of expansion valves were discussed with the temperature distribution of each zone in the evaporator and the superheat changes of the evaporator outlet In each zone temperature distribution fluctuated larger with the thermostatic expansion valve than with the electronic expansion valves. The optimum superheat ranged from $5^{\circ}C\;to\;15^{\circ}C$, and the superheat with the thermostatic expansion valve showed hunting phenomenon, which affected the evaporating and condensing temperature.

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The Study on Performance Characteristics of NH3 Refrigeration System Using Optimum Heat Exchanger (고밀도 열교환기를 이용한 $NH_3$냉동장치의 성능 특성 연구)

  • Lee, Seung-Jae;Jeon, Sang-Sin;Kwon, Il-Wook;Lee, Jong-In;Ha, Ok-Nam
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1276-1281
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    • 2004
  • Nowadays CFCs and HCFCs refrigerants are restricted because it cause depletion of ozone layer. Accordingly, this experiment apply the ammonia gas and not CFCs and HCFCs for refrigerant to study the performance characteristic from the superheat control and improve the energy efficiency from the high performance. The condensing pressure of refrigeration system is increased from 15.0bar to 16bar by 0.5bar and superheat temperature is increased from $0^{\circ}C$ to $10^{\circ}C$ by $1^{\circ}C$ at each condensing pressure. As the result of experiment, when the superheat temperature is $0^{\circ}C$ at each condensing pressure, the refrigeration system has the high performance.

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The Study on Performance Characteristics of Superheating the Suction Vapor in $NH_3$ Refrigeration System ($NH_3$ 냉동장치의 과열도 변화에 의한 성능 특성 연구)

  • 권일욱;하옥남
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.8
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    • pp.756-761
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    • 2004
  • Since the use of CFC and HCFC refrigerants are to be restricted due to the depletion of ozone layer, this experiment applies the NH$_3$ gas to study the performance characteristics from the superheat control for improving the energy efficiency. The experiments are carried out for the condensing pressure of refrigeration system from 14.5 bar to 16.0 bar by 0.5 bar and for superheat temperature from $0^{\circ}C$ to 1$0^{\circ}C$ by 1$^{\circ}C$ at each condensing pressure. As a result of experiment, when the superheat temperature is 1$^{\circ}C$ at each condensing pressure, the refrigeration system has the highest performance.

An Experimental Study on Performance Characteristics of Refrigeration System Using R134a Refrigerating System (R134a를 이용한 냉동장치의 성능특성에 관한 실험적 연구)

  • Kim, Jin-Hyun;Kim, Jong-Kil;Kim, Sung-Bae;Ha, Ok-Nam
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2188-2193
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    • 2007
  • Since the use of CFCs and HCFCs refrigerants are to be restricted due to the depletion of ozone layer, this experiment applies the R134a gas to study the performance characteristic from the superheat control for improving the energy efficiency. The experiments are carried out for the condensing pressure of refrigeration system from 1.5 MPa to 1.6 MPa by 0.05 MPa and for superheat temperature from 0$^{\circ}C$ to 5$^{\circ}C$ by 1$^{\circ}C$ at each condensing pressure. As a result of experiment, when the superheat temperature is 1$^{\circ}C$ at each condensing pressure, the refrigeration system has the highest performance.

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Effects of the Temperature Glide and Superheat of R407C on the Performance of Evaporator (R407C의 온도구배와 과열도가 증발기 성능에 미치는 영향)

  • 김창덕;전창덕;이진호
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.10
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    • pp.852-859
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    • 2003
  • R407C is considered as an alternative refrigerant of R22 for air conditioners. An experiment was carried out to investigate the characteristics of the evaporation heat transfer and pressure drop for refrigerant R407C flowing in a fin-and-tube heat exchanger used for commercial air-conditioning unit. The experimental data were useful in analyze the effects of the temperature glide and superheat for R407C. Test were conducted at the conditions of inlet refrigerant evaporation temperature of 7$^{\circ}C$, inlet air relative humidity of 50%, and refrigerant mass fluxes varying from 150 to 250 kg/m$^2$s. Representative results show that the heat exchanger performance for R407C evaporation is significantly affected by the change of the flow pattern from two-phase to super-heated vapor flow.

Spray Characteristics of a Pressure Swirl Nozzle for an Ambient Condition due to Flash Boiling (감압 비등에 의한 상압 환경에서의 압력식 와류 노즐의 분무 특성)

  • Kim, Won-Ho;Yoon, Woong-Sup
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.686-691
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    • 2010
  • Flash boiling takes place when the thermodynamic state of the liquid deviates from its saturation limit over which the liquid temperature exceeds by a certain degree of superheat. The liquid jet introduced into the lower pressure zone than the liquid saturation pressure experiences a sequence of the atomization and disintegrated into numerous faster and smaller droplets. In the present study spray characteristics for a flash swirl spray were experimentally investigated. Injectant temperature is raised by a high frequency dielectric heating method and local spray characteristics are instantly measured by Global Sizing Velocimetry (GSV, TSI Inc.). Dependence of dimensionless superheat degree and injection pressure on total and local SMDs and mean droplet size is quantitatively examined. The flash swirl spray has the relation in the injection pressure and nozzle diameter in order to determine the spray quality, including the dimensionless superheat degree. Small droplets occur in the void core and local droplet size distributions largely depend on the dimensionless superheat degree and the injection pressure.

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