How does a fan-coil chiller system with thermo-accumulation work and why is it used?

In these systems the environment to be air-conditioned exchanges heat with an equipment consisting of a coil and a fan (coil). Cold water circulates from the chiller through the serpentine. The thermal exchange involved in fan-coil is only in the sensible form. Generally the water enters the fan-coil at a temperature of 7 ° C and exits at a temperature of 12 ° C. The heat withdrawn from the air-conditioned environment is carried through the circulating water is exchanged with the refrigerant fluid in the chiller evaporator. This refrigerant is condensed through the use of a flow of water circulating through a cooling tower. The water flow needed for this process can be calculated either by knowing the properties of the refrigerant or by the equation of the sensible heat exchange applied to the water. A typical composition of this system with ice accumulators is widely used to save energy during times of peak electricity consumption. The chiller system is used to make ice during dawn at a lower energy cost. Ice water from the fan coil is diverted to traverse the ice tanks, making them play the role of the chiller in the late afternoon and early evening when the cost of electricity is higher.