This paper focuses on the simulation of refrigeration cycle equipped with the adiabatic capillary tube, which is widely used in small vapor compression refrigeration systems. The present simulation is based on fundamental conservation equations of mass, energy and momentum. These equations are solved through an iterative process. The adiabatic capillary tube model is based on homogeneous flow model. This model is used to understand the natural refrigerants flow behavior inside the adiabatic capillary tube. Transport properties and thermodynamic of natural refrigerants are calculated by using EES(Engineering Equation Solver) program. The operating factors considered in this paper include condensation temperature, evaporation temperature, inner diameter tube and sub-cooling degree of the adiabatic capillary tube. Our simulation results are summarized as follows: as the size of the inner diameter tube increases, the pressure drop in the capillary tube decreases while the length of the capillary tube increases. We found that R-290 decreases by 20-22% on average, and R-600a significantly decreases below 50%, while R-1270 increases 17-19% on average, compared to R-134a.

Recently, self-propagating high-temperature synthesis (SHS), related to metallic and ceramic powder inter- actions, has attracted huge interest from more and more researchers, because it can provide an attractive, energy-efficient approach to the synthesis of simple and complex materials. The adiabatic temperature Tad and apparent activation energy analysis of different thermit systems plays an important role in thermodynamic studies on combustion synthesis. After establishing and verifying a mathematic calculation program for predicting adiabatic temperatures, based on the thermo- dynamic theory of combustion synthesis systems, the adiabatic temperatures of the NiO/Al aluminothermic system dur- ing self-propagating high-temperature synthesis were investigated. The effect of a diluting agent additive fraction on combustion velocity was studied. According to the simulation and experimental results, the apparent activation energy was estimated using the Arrhenius diagram of ln(v/Tad)~1/Tad based on the combustion equation given by Merzhanov et al. When the temperature exceeds the boiling point of aluminum (2,790 K), the apparent activation energy of the NiO/ Al aluminothermic system is 64 ± 14 kJ/mol. In contrast, below 2,790 K, the apparent activation energy is 189 ± 15 kJ/ mol. The process of combustion contributed to the mass-transference of aluminum reactant of the burning compacts. The reliability of the simulation results was experimentally verified.

본 연구의 목적은 고등학교 지구과학 I의 단열변화 주제에 관한 교과서별 내용을 분석하여 향후 교과서 집필 방향에 시사점을 제공하기 위한 것이다. 연구를 위하여 8종의 고등학교 검인정 과학 교과서 중, 일선 학교에서 많이 사용하고 있는 6종의 교과서를 분석 대상으로 선정하였다. 교과서 분석에는 전주시 소재의 교원 양성 대학교에 재학 중인 예비교사 35명이 참여하였다. 먼저 연구자가 사전에 6종의 분석대상 교과서를 살핀 후, 분석관점을 단열변화에 대한 개념 정의, 단열변화에 대한 삽화, 단열변화에 대한 실험의 세 부분으로 범주화하였다. 이를 바탕으로 6종의 교과서를 분석한 후 각 범주별로 가장 우수한 교과서를 선정하였다. 연구 결과 단열변화에 대한 개념정의는 교과서 A, 단열변화에 대한 삽화는 교과서 C, 단열변화에 대한 실험은 교과서 B가 우수한 것으로 선정되었으며, 6종의 교과서 모두 불완전한 부분이 있음이 확인되었다. 이러한 교과서의 부정확성, 부적절성은 학생들이 단열변화를 이해하는 데 어려움을 초래할 수 있으며, 더 나아가 오개념을 형성하도록 하는 문제점을 가져올 수 있다. 따라서 단열변화에 대한 보다 체계적이고 정확하며, 완전한 내용이 담겨지도록 교과서의 내용을 재구성할 필요성이 있다.

Because of building higher story and larger buildings, and because current concrete, a basic construction material, needs higher strength rather than normal strength, the use of high-strength concrete becomes more widely spread. High-strength concrete shows very high temperature increase due to inside heat of hydration different from normal-strength concrete, and because mass concrete under low temperature shows temperature stress due to temperature difference between inner and outer parts, it is known or reported that there is a significant difference between the compressive strength of srtucture and that of specimen for management, and between the compressivestrength of circular specimen made by standard underwater curing and structure concrete Therefore, in this research, an adiabatic curing box was manufactured which can provide hydration heat hysteresis of high strength mass concrete members and similar hydration heat hysteresis, using insulating materials, as a easy and exact method to manage compressive strength of rnass concrete member under low temperature, and the features of concrete member and those of specimen for management were compared.

The purpose of this study is to investigate correation between semi-adiabatic temperature and adiabatic temperature rise of ordinary portland cement(OPC) and ternary blended cement(TBC). And concrete adiabatic temperature rise factor was estimated by semi-hydration heat analysis test.

Experimental program was conducted for hydration heat evaluation of concrete using strontium based phase change material (PCM). Adiabatic temperature rise test was investigated for four days. In results, concrete with strontium based PCM has about 20 percent lower hydration heat than ordinary one.

In this study, we intended to estimate the heat of hydration of carbon nanotubes-cement composites. It was tried to present the basic data of the heat of hydration characteristics of the CNT-reinforced cement composite by the simple adiabatic temperature rise test. The results indicated that adding CNT reduced the heat of hydration of cement composites.