Abstract
The present investigation was undertaken to apply the finite difference methods to the ventilation of polluted air in rooms. Linear finite difference equation of the first order is U (t+1)=a {U (t)+b}, where U (t) and U (t+1) are the concentrations of carbondioxide in rooms at t and (t+1) hours respectively, and a is a ventilation constant (a〓0), b is the volume of carbon dioxide produced per hour. The general solution above equation is U (t)=Cat+U*, where U* is equilibrium value, C is the arbitrary constant, and t is time, in case of |a|<1, U (t) converges on U*. Results of the experiment indicate that a is 0.19 (A-room) and 0.21 (B-room) respectively, and U* is 0.75 ml/l. The investigation has demonstrated that the finite difference equation for calculation of ventilation is successfully used in place of the equation of exponential function.
