압축기 계가 결합된 응축기의 동특성

김재돌,Kim, Jae-Dol 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.7

This paper reports the analysis of dynamic characteristics of air-cooled condenser. At first, there is an assumption that the superheated vapor flows into the condenser inlet. And in order to consider the effect of pressure change in the dynamic characteristics of the condenser the combined system of condenser and compressor was used. By using the equation of energy balance and the equation of mass balance, the basic equation for describing the dynamic characteristics of condenser can be derived. The transfer function for describing dynamic response of the condenser to flow rate change outlet can be obtained from using linearizations and Laplace transformations of the equation. From this transfer function, analytical investigation which affects the frequency responses of condenser has been made. Through this study, it became possible that the information about the dynamic characteristics of air-cooled condenser is offered. While the average heat transfer coefficient of the refrigerant side necessary for the theoretical calculation of the dynamic characteristics is given by calculation method for the tube length and pressure drop of air-cooled condenser.

2단압축 냉동장치의 성능특성에 관한 실험적 연구

김재돌,오후규,김성규,권옥배 한국마린엔지니어링학회 1994 한국마린엔지니어링학회지 Vol.18 No.2

The characteristics of the R-22 two-stage compression refrigeration systems were investigated. The apparatus consisted of 0.5HP and 1HP hermetic reciprocating compressors for the high and low stage sides respectively, a condenser, an evaporator, a heat exchanger, four expansion valves, and two intercoolers. The experiments covered a range of refrigerant flow rates from 24 to 84kg/h, and the inlet temperature of cooling water in the condenser and heat source water in the evaporator ranged from 20 to 30$^.\circ}C$The results Showed that the refrigerant flow rate had greater effect on the refrigerating capacities, the compression efficiency and the coefficient of performance of two-stage compression systems than the inlet temperature of heat source water. And all these values were decreased with increasing inlet temperatures of the cooling water. The pressure drops in the evaporator of two-stage compression systems were decreased in proportion to the increase in the inlet temperature of the heat source and cooling water, but it was increased by the refrigerant flow rate.

빙축열시스템용 유화용액 축열재의 유동 및 온도특성

김재돌,윤정인 한국건축설비학회 1998 건축 설비 Vol.1 No.3

열에너지를 저장하는 축열 시스템은 공조설비 등에 이용되고 있는 유용한 방법의 하나이다. 이는 여름철 주간 전력의 피크컷(peak cut), 열원기기의 용량 축소, 열원기기 고장시의 대응 등을 목적으로 채용하는 경우가 많으며, 에너지 절약 및 유지비 절감 등의 가능성도 있다. 축열시스템은 크게 현열형(sensible heat type)과 잠열형(latent heat type)으로 나눌 수 있다. 전자는 온도차에 의한 방법으로 냉수, 온수, 건물 구조체, 암석 등이 있으며, 후자는 상변화를 이용한 것으로 얼음이나 잠열 축열재(유치화합물, 파라핀 등)가 여기에 해당된다. 물을 축열재로하는 시스템은 화학적으로 안정하고, 자원이 풍부한 등 여러가지 장점을 가지고 있지만 설비가 커지고, 축열조에서의 열손실이 큰 점 등의 결점이 있다. 한편 빙축열은 물이 얼음으로 상변화할때의 잠열을 이용한 것으로 이 잠열은 현열에 비해 약 80배 정도로 커 적은 체적으로도 효율적인 냉열저장이 가능하다. 또한 축열조의 소형화와 단열의 간편성 때문에 방열손실에 대해 유리하며, 일정온도의 열을 용이하게 이용할 수 있는 장점도 있다. 그러나, 빙축열시스템은 물을 냉각하여 얼음을 생성하는 축냉과정에서 과냉각이 발생하면 일정온도의 열에너지를 고효율로 축적할 수 있는 잠열 축열재로서의 장점을 잃게 된다. 따라서, 본 연구에서는 방축열시스템에 있어 최대의 결점인 과냉각에 의한 냉각온도의 저하로 소요전력의 증가와 얼음의 성장에 따른 열저항의 증대를 극복하기 위한 한 방법으로써 유동성을 가진 얼음의 이용을 고려하였다. 이 방법은 기름, 물, 계면활성제에 의한 다성분 혼합용액을 유화(乳化)냉각하는 것으로 과냉각이나 열저항에 의한 소요전력의 증대를 막을 뿐만 아니라, 혼합유체를 직접 유통시키기 때문에 고효율의 새로운 축열재 개발을 기대할 수 있다. 이와 같은 관점에서 다성분 혼합용액의 냉각에 의한 유동성이 있는 얼음의 생성 및 온도특성에 관한 실험을 통하여 빙축열시스템용 축열재 개발의 가능성을 제시하였다. A fundamental study on ice formation and its temperature characteristics in ice storage system was performed experimentally. In case of ice formation, failing of cooling temperature due to supercooling causes the inereasement of electricity consumption and thermal resistance which restrains the growth of ice. For these reasons, we took the ice with movement into consideration by using the mixture which contains oil, water, and surfactant. From the experimental results, it is possible to make use of the latent heat of mixture because the freezing phenomenon of mixture was almost alike in movement and solidification point maintenance time in comparison with water. Especially, the addition of ethyleneglycol brought the movement into the mixture. On the other hand, this made no use of the latent heat of mixture.

공조기 제어를 위한 응축기의 동특성 해석

김재돌,윤정인,통구 김차랑,Kim, J.D.,Yoon, J.I.,Higuchi, K. 대한설비공학회 1996 설비공학 논문집 Vol.8 No.3

The dynamic characteristics of a condenser are numerically studied for the control of air-conditioning systems. The important factors, such as the refrigerant flow rate and refrigerant temperature, air velocity and air temperature at the condenser inlet, are incorporated into the analysis. This study was focused on the analysis of dynamic responses by transfer function method in the condenser. Block diagrams were made through analytic transfer function, and dynamic responses are evaluated on Bode diagrams in the frequency response. These results may be used for determining an optimum design parameters in an actual component and total systems. Also, the mathematical models, frequency response and steady state response may be used to increase understanding, to obtain useful information for its commercialization, to evaluate the hardware and the optimum design parameters, the design control system and to determine the best controller setting for the refrigeration and air conditioning systems.

모세관 삽입 룸 에어컨용 액.가스 열교환 배관에 관한 실험적 연구

김재돌,Kim, Jae-Dol 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.6

This study shows the experimental characteristics of the double pipe inserted liquid pipe with small diameter in the gas pipe with large diameter for circulating of a liquid of high temperature, pressure and a gas of low temperature, pressure at the same time. So the functions of pipe and pipe's expansion and heat transfer are presented simultaneously. In the result, the temperature of gas refrigerant at the inlet of compressor increased about $5^{\circ}C$ by the heat transfer with liquid refrigerant in case of the double pipe. And liquid gas refrigerant which the temperature at the inlet of evaporator decreased about $3^{\circ}C$ comparing with the existing type flows into an evaporator COP of the double pipe increased about $7{\sim}10%$ comparing with that of the conventional pipe. And the noise of the double pipe at capillary tube is less than that of the conventional type about 3dB. Consequently. it is convinced the superiority of the double pipe in the heat loss and soundproofing aspect.

실내 부하 변동에 따른 탄화수소계 냉매를 이용한 히트펌프 성능에 관한 실험적 연구

김재돌,성광훈,정석권,윤정인,이호생,Kim, Jae-Dol,Seong, Gwang-Hoon,Jeong, Seok-Kwon,Yoon, Jung-In,Lee, Ho-Saeng 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.2

This study presents heat pump system characteristics using hydrocarbon refrigerants as alternative refrigerant for R-22 with respect to the variation of indoor load. Pure R-22 and R-290. R-600a, R-1270 were considered as working fluids The experimental apparatus was constructed to investigate the performance of heat pump using the air as a heat source. The performance were calculated based on compression shaft work. refrigeration capacity. pressure ratio, discharge temperature and COP. The experimental results show that the COP and refrigeration capacity of hydrocarbon refrigerants were higher than that of R-22. Through the above. hydrocarbon refrigerants are good alternatives in the heat pump system for R-22.

소형 공조용 응축기의 특성 해석

김재돌,장재은,윤정인 한국에너지학회 1999 에너지공학 Vol.8 No.1

본 연구는 일반적으로 소·중용량의 냉동·공조기에 많이 사용되고 있는 플레이트 핀 코일형 공냉응축기를 대상으로 수치해석에 의해 응축기의 특성을 파악하였다. 해석에서는 응축기를 과열증기영역, 2상영역 및 과냉각액영역으로 구분하여 공냉 응축기의 성능에 큰 영향을 미치고 있는 공기온도, 공기측열전달률, 입구 냉매온도, 응축온도 및 질량유량 등을 파라메터로하여 이들의 상호관계와 이들이 응축완료점까지의 거리 및 방열량 등에 미치는 영향을 파악하였다. 해석결과로는 해석모델로부터 각 영역의 냉매 상태량, 온도분포 및 열전달률을 구할 수 있었고, 일반적으로 응축기의 성능에 많은 영향을 미치는 각종 파라메터들을 중심으로 광범위한 동작조건에서 이들의 상관관계 및 특성을 파악하므로서 응축기 설계를 위한 기초 자료 및 설치장소나 주위환경 등에 따라 서로간에 다양한 영향을 미치는 실제장치의 동적특성 해석을 위한 자료를 얻을 수 있었다.

탄화수소계 냉매의 응축 압력강하에 관한 연구

김재돌,최준혁,정석권,윤정인,이호생,Kim, Jae-Dol,Choi, Jun-Hyuk,Jeong, Seok-Kwon,Yoon, Jung-In,Lee, Ho-Saeng 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.2

Experimental results for pressure gradient of HCs refrigerants R-290. R-600a. R-1270 and HCFC refrigerant R-22 during condensing inside horizontal double pipe heat exchangers are presented. The test sections which have the tube inner diameter of 10.98mm. and the tube inner diameter of 8mm are used for this investigation. Hydrocarbon refrigerants have higher pressure drop than R-22 in both test sections with the diameters of 12.70mm and 9.52mm. Pressure drop increased with the increase of the mass flux. These results form the investigation can be used in the design of heat transfer exchanger using hydrocarbons as the refrigerant for the air-conditioning systems

멀티 공조시스템의 최적 제어를 위한 기초 연구 - 응축기의 동특성 해석 - ( A Study on Optimal Control of Multi-Air Conditioning System - Analysis of Dynamic Characteristics on Condenser - )

김재돌,오후규,윤정인,구학근 대한기계학회 1996 대한기계학회 춘추학술대회 Vol.- No.-

증발기 과열도제어에 따른 냉동장치의 동특성에 관한 연구

김재돌,오후규,윤정인 대한기계학회 1995 대한기계학회논문집 Vol.19 No.8

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.