Specific heat capacity of ice

Ice stores about half as much heat per kelvin as liquid water, because the hydrogen bond network is already locked in place and cannot absorb energy by rearranging. The value is strongly temperature dependent, falling roughly linearly to about 2.05 kJ/(kg·K) at −20 °C and 1.94 at −40 °C, so refrigeration calculations that span a wide range should integrate rather than use a single figure.

In cold-storage and freeze-protection work the three terms come in sequence: cool the water to 0 °C at 4.18 kJ/(kg·K), remove the latent heat of fusion at 334 kJ/kg, then cool the ice at 2.11 kJ/(kg·K). The latent step dominates — it is worth about 80 K of sensible cooling — which is why ice storage systems are economically interesting and why a partially frozen coil takes so long to clear.