US Patent 7836721 Cooling system

A cooling system (10) comprises a first (40) and a second (50) cold storage tank, a first refrigerator (41) cooling water in the first cold storage tank (40), a first thermal load (92) disposed in a first circulating passage (43) extending from the lower to the upper part of the first cold storage (40), a second thermal load (93) warmer than the first thermal load (92) disposed in a second circulating passage (44a) also extending from the lower to the upper part of the first cold storage tank, a second cold storage tank (50) disposed in the second circulating passage, a second refrigerator (51) cooling water fed from the upper part of the second cold storage (50), wherein a cooling output temperature of the second refrigerator (51) is set to be higher than that of the first refrigerator (41).