Patent ID: 7832217

Claim:
A Method of Controlling an ice formation process of a thermal energy module, said thermal energy module comprising a tank, said tank comprising a first heat exchanger and water, said first heat exchanger comprising liquid refrigerant, refrigerant vapor, and a first heat-exchange surface for exchanging heat between the water and the liquid refrigerant, a suction line attached to the first heat exchanger adapted to remove the refrigerant vapor from the first heat exchanger, and a pressure sensor placed within the suction line adapted to measure the pressure of the refrigerant vapor, said method comprising: experimentally deriving a correction coefficient (K) for the first heat exchanger; injecting liquid refrigerant into the first heat exchanger; removing refrigerant vapor from the first heat exchanger through the suction line; forming ice on the first heat-exchange surface; measuring the pressure of the refrigerant vapor; deriving the saturation temperature (Tr) of the refrigerant vapor corresponding to the pressure of the refrigerant vapor; calculating an integral of saturation temperature I(t) according to a first equation: I(t)=∫Tr(τ)*dτ, where Tr is the saturation temperature of the refrigerant which varies with time (t) and the integral of saturation temperature is taken over a period of time that begins with the start of the ice formation process; calculating a thickness of ice X(t) according to a second equation: X(t)=√(2*I(t)*K*Ui/ρi/ci), where Ui is a variable representing a thermal conductance of ice, ρi is a variable representing a density of ice, and ci is a variable representing a latent heat of ice; establishing a desired thickness of ice; and suspending the ice formation process when the calculated thickness of ice X(t) reaches the desired thickness of ice.