Cooling systems and methods

A cooling system 112 comprises a refrigerator 114, a fluid vessel 116, a fluid flow driving means such as a pump 146, thermal transfer means such as a heat exchanger 120, and first and second power supplies. The refrigerator is powered by the first power supply, which may be a mains power supply, and is provided for cooling a fluid which is contained in the fluid vessel. The fluid flow driving means is powered by the second power supply, which may be a battery, and is provided for generating a flow of fluid in the system. The thermal transfer means is adapted to exchange heat with an item to be cooled, such as the warm air of a computer server room or another cooling system. The fluid flow driving means operates in response to a loss of the first power supply, perhaps in the event of a power cut or outage, to pump cooled fluid through the thermal transfer means. In further aspects, a cooling system is provided as a secondary or back-up cooling system for cooling at least one primary cooling system, so as to reduce the temperature of coolant in the primary system. In the secondary cooling system, the fluid transport means can operate in response to a signal produced by a sensor. Preferably, the cooling systems are used as part of an uninterruptible power supply (UPS).