surface. Dry expansion coils for immersion in an open tank will be in a continuous circuit or a number of parallel circuits (see Figure 7.6). Liquid velocity over such coils can be increased by tank baffles and there may be special purpose agitators, as in an icemaking tank (see Figure 12.1). Coils within an open tank can be allowed to collect a layer of ice during off-load periods, thus providing thermal storage and giving a reserve of cooling capacity at peak load times (see also Chapter 12).