New approach for Finite Difference Method for Thermal Analysis of   Passive Solar Systems
  Mathematical treatment of massive wall systems is a useful tool for investigation of these solar applications. The objectives of this work are to develop (and validate) a numerical solution model for predication the thermal behaviour of passive solar systems with massive wall, to improve knowledge of using indirect passive solar systems and assess its energy efficiency according to climatic conditions in Bulgaria. The problem of passive solar systems with massive walls is modelled by thermal and mass transfer equations. As a boundary conditions for the mathematical problem are used equations, which describe influence of weather data and constructive parameters of building on the thermal performance of the passive system. The mathematical model is solved by means of finite differences method and improved solution procedure. In article are presented results of theoretical and experimental study for developing and validating a numerical solution model for predication the thermal behaviour of passive solar systems with massive wall. 
Stanko Shtrakov and Anton Stoilov