Kyushu University · 공학
Ryo Akasaka 교수의 연구실은 열물성 및 열역학적 성질을 정밀하게 예측하기 위한 헬름홀츠 자유에너지 기반의 상태방정식 개발에 주력하고 있습니다. 특히 냉매 물질인 R-1234ze(Z), R-245fa, R-1243zf, R-1233zd(E) 등의 고정밀 상태방정식을 실험 데이터 기반으로 최적화하고 있으며, 비정상적인 조건(고온·고압, 임계점 근처)에서도 높은 정확도를 확보합니다. 또한, 임계점 근처에서의 포화상태 계산을 위한 고도화된 수치적 해법(뉴턴-라프슨 방법 등) 개발을 통해 열역학적 데이터의 신뢰성을 강화하고 있습니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
New fundamental equations of state are presented for cis-1,3,3,3-tetrafluoropropene [R-1234ze(Z)] and 3,3,3-trifluoropropene (R-1243zf). The new equation for R-1234ze(Z), which is the main topic of this paper, is applicable to ranges at lower temperatures and higher pressures compared to the first published equation, and uncertainties in liquid-phase sound speeds are greatly improved. The equation is valid at temperatures from 238 to 440 K at pressures up to 34 MPa. Estimated uncertainties in th
A new fundamental equation of state explicit in the Helmholtz energy is presented for 1,1,1,3,3-pentafluoropropane (R-245fa), based on recent experimental data for vapor pressures, densities, and sound speeds. The functional form uses Gaussian bell-shaped terms, according to recent trends in the development of accurate equations of state. The independent variables of the equation of state are temperature and density. The equation is valid for temperatures between the triple point (170.0 K) and 4
Recent trends in the development of Helmholtz energy equations of state are briefly reviewed. Optimization procedures have been improved over the last two decades, and now nonlinear least-square fitting is effectively used in the optimization. This fitting technique makes it possible to develop a reliable equation of state for fluids with limited experimental data. The fitting is demonstrated for 3,3,3-trifluoroprop-1-ene (R-1243zf; CAS number 677-21-4). Experimental data for the critical parame
This paper discusses iterative calculation methods to determine the saturation state of pure fluids by using Helmholtz energy equations of state. The commonly used method is based on the successive substitution approach. This method is simple, but requires an aid of ancillary equations to estimate sufficiently accurate initial guesses for the saturation pressure and saturated liquid and vapor densities. In particular, in the vicinity of the critical point very accurate initial guesses are needed
