A METHOD OF MAINTAINING THE ZONE TEMPERATURE IN A VARIABLE AIR VOLUME AIR CONDITIONING SYSTEM AND A SYSTEM THEREOF

摘要

The invention relates to A method of maintaining the zone temperature in a variable air volume air conditioning (VAVAC) system with optimized power consumption comprising the steps of determining the power consumption of the fan of an Air handling unit (AHU) of said VAVAC system as a function of said fan speed at a given cooling load; determining the power consumption of a chiller of said VAVAC system as a function of the temperature of a chilled water storage tank at said cooling load, total power consumption at said cooling load being derived by summation of said two powers for feeding to a control means; identifying the minimum of said total power function by ascertaining the derivative of the power function and setting the derivative to zero; repeating steps at (a), (b), & (c) for every cooling load between 100 watt to 3000 watt to ascertain the optimal fan speed and the minimum power consumption as a function of the temperature of said chilled water storage tank; determining an objective function in said control means for different values of fan speed with varying cooling load, the objective function being subjected to minimization being an unimodal function; selecting a starting point at the minimum value of a feasible boundary region and applying a direct search technique in said control means to obtain an optimal set point; continuing said search technique using a fixed step-size of a plurality of different starting point and moving towards a favourable direction; selecting a guess point being the minimum fan speed and evaluating the objective function at said guess point; determining a new guess point by adding said step-size to said initial guess point and further evaluating the objective function at said new guess point; proceeding with a minimization step of the objective function in said direction in case the determined value of said objective function emerging as lower than the value of earlier said objective function; continuing said searching step until said new guess point shows an increased value of said objective function determined at step (j) the search being continued up to a point Xi, the value of Xi being equal to Xi + (i-l)S, where 'S' represents the step-size and i representing the number of iterations; terminating said search at said point Xi where the increase in the objective function is indicated.[IN242236A1]