• 한국산학기술학회논문지
• /
• 제10권4호
• /
• pp.740-746
• /
• 2009

본 논문에서는 공진형 유도가열기를 이용한 2단 직렬 부하형 유도가열 과열증기 발생장치를 제안하였다. 발열방식은 외부의 가열코일로부터 특수 합금 발열체에 비접촉 상태로 전자유도 와전류를 구조체에 흐르게 하였다. 인버터는 풀-브리지 고주파 직렬 부하 공진형 이며, LC 공진 설계에서 부하자체를 인덕터로 선정하여 효율을 최대화 하였다. 개발된 장치는 전자유도가열 발열체와 유체이동에 의한 새로운 열교환 방식으로 일체의 연소과정 없이 기체, 액체 및 증발체 등을 상온에서 고온에 이르기까지 고정도의 가열이 가능하다.

• 한국태양에너지학회 논문집
• /
• 제29권5호
• /
• pp.8-13
• /
• 2009

Feasibilities of the application of a micro gas turbine cogeneration system to a large size hospital building are studied by estimating energy demands and supplies. The energy demand for electricity is estimated by surveying and sorting the consumption records for various equipment and devices. The cooling heating, and hot water demands are further refined with TRNSYS and ESP-r to generate load profiles for the subsequent operation simulations. The operation of the suggested cogeneration system in conjunction with the load data is simulated for a time span of a year to predict energy consumption and gain profile. The simulation revealed that the thermal efficiency of the gas turbine is about 30% and it supplies 60% of the electricity required by the building. The recovered heat can meet 56% of total heating load and 67% of cooling, and the combined efficiency reaches up to 70%.

• 동력기계공학회지
• /
• 제18권1호
• /
• pp.45-50
• /
• 2014

This study focuses on the analysis of the cooling and heating load in accordance with apartment houses arrangement type using Ecotect Analysis. Korea have to reduce energy consumption part of building except in industry and transport because the rate of dependence on imports amounts to 94%, Apartment houses built in various forms in order to reduce energy are modelled in each window area ratio, shape, orientation, and climate through simulation. Through this study, we can analyze the cooling and heating load by form, window area ratio, orientation, and climate change and know the optimal elements by the form. In particular, although there have been done research on the window area ratio and the arrangement form, the research of the regional climate characteristics and the direction are hardly carried out. To supplement those problem, adding to seven direction and climatic element of southern region is characteristic(L Type, Y Type, - Type) of this study. The form of apartment houses built 10 years ago is modelled for simulation.

• KIEAE Journal
• /
• 제12권6호
• /
• pp.29-38
• /
• 2012

The current building energy efficiency rating certification regulation on apartment houses evaluates only the saving rate of energy consumed during operation, i.e. use, of a building, but doesn't consider the energy consumptions and environmental load($CO_2$) emissions occurring during the whole lifetime of a building. So this study calculated the energy consumptions and environmental load emissions occurring during the whole lifetime of a building, selected reference schemes and alternative items by design variables to present a design draft considering energy efficiency and environmental performance, and evaluated the total cost by combining and calculating its direct cost(material and heating cost) and indirect cost(environmental cost), for an existing apartment house as an evaluation object. As a result of analysis, the change of heating cost by alternative items of design variables showed a 4~8% change rate compared to the reference scheme, and the material cost of design variable 7 showed a maximum 4.4 times change rate in the alternative plan 6 compared to the reference scheme. The environmental cost showed a similar change rate to the material cost change rate in general, but showed a similar environmental cost change rate to the heating cost change rate in case of design variables 4-1, 4-2, 7.

• 한국조명전기설비학회지:조명전기설비
• /
• 제11권6호
• /
• pp.90-95
• /
• 1997

고주파 유도가열을 위한 인버터의 공진회로 설계에서 인덕턴스 L의 작용과, 출력전달 요소로 사용된 변압기의 결합계수, 그리고 코일을 사용한 가열부하의 결합계수가 공진회로의 출력, 회로의 Q와 공진주파수에 큰 영향을 주고 있음을 등가회로를 도출하여 그 특성을 해석하였다. 또한 변압기를 테브난 등가회로로 구성할 경우, 변압기의 이차측 임피던스를 일차측 임피던스고 환산하면, 권선비 n$^2$에 비례 할 뿐만 아니라 결합계수 $K^2$에도 비례함을 도출하여 결합계수형 테브난 등가회로에 의한 정확성이 큰 인버터 공진회로 설계의 기초방식을 나타냈다.

• Journal of Power Electronics
• /
• 제15권1호
• /
• pp.65-77
• /
• 2015

Resonant converters are well suited for induction heating (IH) applications due to their advantages such as efficiency and power density. The control systems of these appliances should provide smooth and wide power control with fewer losses. In this paper, a simple phase locked loop (PLL) based variable duty cycle (VDC) pulse density modulation (PDM) power control scheme for use in class-D inverters for IH loads is proposed. This VDC PDM control method provides a wide power control range. This control scheme also achieves stable and efficient Zero-Voltage-Switching (ZVS) operation over a wide load range. Analysis and modeling of an IH load is done to perform a time domain simulation. The design and output power analysis of a class-D inverter are done for both the conventional pulse width modulation (PWM) and the proposed PLL based VDC PDM methods. The control principles of the proposed method are described in detail. The validity of the proposed control scheme is verified through MATLAB simulations. The PLL loop maintains operation closer to the resonant frequency irrespective of variations in the load parameters. The proposed control scheme provides a linear output power variation to simplify the control logic. A prototype of the class-D inverter system is implemented to validate the simulation results.

• 기술사
• /
• 제33권1호
• /
• pp.94-105
• /
• 2000

The purpose of this paper is to obtain the improved reliability and optimal control of the half-bridge inverter for induction heating system. Parasitic inductance components within the inverter circuit for induction heating including the loss-less turn-off snubber capacitor considerably affect stable operation and noise level of the system. This paper analyzes the effect of the inductance in detail and presents a new snubber configuration suitable for the half-bridge inverter to effectively reduce it. In the half-bridge inverter for induction heating the capacity of the loss-less snubber capacitor determines the switching losses because the zero voltage turn-on switching is used. However, the increase of the capacitor is limited by the system specifications, so that it is not easy work to reduce the switching loss. To effectively overcome the limitation, this paper introduces an active auxiliary resonant circuit suitable for the half-bridge inverter circuit, which operates actively according to the variation of load condition. It is also one of the most important study issues for the half-bridge inverter driven induction heater that the development of optimal control scheme considering varied load condition should be achieved. The control strategy ensures a very stable operation of overall inverter system and zero voltage turn-on switching irrespective of sensitive load parameter variations, in particular, even under the non-magnetic materials.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2021년도 가을 학술논문 발표대회
• /
• pp.234-235
• /
• 2021

We set the representative balcony types of the existed building to two types: unexpanded balcony and extended balcony, and analyze the effect of reducing the cooling and heating energy load when applying remodeling. The scope of the study was limited to balcony walls, including window-wall junctions, and was conducted by comparing cases with and without thermal break insulation structures for a clear conclusion. The study was conducted using the equivalent U-value in each case. The equivalent U-value was calculated by deriving through 2 dimensional steady-state heat transfer analysis of each case balcony envelope. And building energy was calculated using the derived equivalent U-value. According to the calculation results, for unexpanded balconies, the equivalent U-value was reduced by about 80%, and the heating and cooling load was reduced by about 20%. In the case of extended balconies, the equivalent U-value was reduced by about 57% and the resulting heating and cooling load was reduced by about 12%.

• 설비공학논문집
• /
• 제15권6호
• /
• pp.454-460
• /
• 2003

In order to investigate the cooling and heating characteristics of a variable-capacity system A/C applying a digital scroll compressor, the cooling and heating capacities and COP are measured by the psychrometric calorimeter. The capacity of the system is controlled by the digital scroll compressor, which is operated by controling PWM valve and the loading vs. unloading time. In the case of unloading compared that of loading, the consumption power of the compressor is about 11% and the capacity variation of the system A/C is within about 1%. When the system A/C is operated under the cooling and heating standard conditions, COP is nearly uniform but cooling capacity and heating capacity increase at minimum, rated and maximum modes. The system A/C applying the digital scroll compressor is effective for the range with high load or the width of large load variation. When the auxiliary heater is on, at the cold region, the system A/C produces the excellent heating capacity.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제10권2호
• /
• pp.65-71
• /
• 2002

The objective of this study is to evaluate the design parameters and to develop the cooling and heating load prediction equations of office buildings. The building load calculation simulation was carried out using the DOE-2.1E program. The results of the simulation were used as data for multiple regression analysis which could develop the load prediction equations.