Aplicativo educacional em interface VBA para simulação de ciclos Rankine em planilha Excel

Abstract

In this work the educational use of the Visual Basic for Applications (VBA) in an Excel spreadsheet was proposed for the thermodynamic study applied to the Rankine cycle, making its learnings ease by the cycle visualization and selection, as well the data insertion and simulation in the selected cycles with relevant parameters variations. The interface inclusion of input data is at the user's discretion, namely: pressure (kPa), temperature (ºC), isentropic efficiency in the pump and turbine. Rankine cycles available are: Simple Rankine cycle (steam input superheated or saturated), Rankine cycle with one reheat (superheated steam inlet), Rankine cycle with two reheats (superheated steam inlet) and ideal Rankine cycle with open regenerator (superheated steam inlet). Simulations were structured via an algorithm programmed in the VBA software, based on the calculation of the specific enthalpy, specific entropy and specific volume thermodynamic properties, as well as the pressure variation (kPa) and / or temperature (ºC), running through user command. Results generated are thermal efficiency (ηt), bwr (back work ratio), steam mass flow (kg/h), Q̇ ent (system inlet heat flow), Q̇ sai (system outlet heat flow) and the pressure or temperature range determined. In the final stage, the values are plotted on a graphic in a spreadsheet according to the thermodynamic state of the studied cycle.