New technology that drastically reduces the power consumption of air-conditioning pumps has been developed by a research team led by Associate Professor Hiroshi Suzuki at the Kobe University Graduate School of Science and Technology and the New Industry Research Organization. This technology involves the addition of hydrate particles and drag-reducing surfactants to the chilled water in air-conditioning systems. Water or liquid dispersed with hydrate particles is called hydrate slurry and is well-suited for cooling applications due to its high latent heat.

Central air-conditioning that cools and heats the entire building has become more common for office buildings because it is more energy-efficient than using individual air-conditioning units. Although centralized systems can be expected to contribute to global warming prevention, it is critical to reduce their power consumption used for pumping, which accounts for 10 to 20 percent of the energy used to generate cooled or heated air at peak operation.

Hydrate slurry has been drawing attention as a possible solution. However its high viscosity, which generates twice the fluid friction resistance of water, has been a hindrance to its practical application. The technology developed this time successfully reduced this friction resistance by using a surfactant.

A feasibility study was conducted to estimate the heat transfer performance of the hydrate slurry air-conditioning system if applied to a 30-story building with two floors below ground. The results showed that the use of slurry containing 20-percent hydrate particles could reduce the flow rate, corresponding to heat load, to one third of that of using water, decreasing the number of pumps from six to two and the diameter of pipes by half, also resulting in savings on valves and piping materials. The addition of surfactant to the fluid flowing through the half-sized pipes also showed a dramatic reduction in power consumption, by as much as about 75%.

http://www.jfe-steel.co.jp/en/research/report/003/pdf/003-02.pdf
http://www.niro.or.jp/n_english/index.html

Posted: 2006/09/23 01:46:11 PM
Japanese version

TAG Energy , Manufacturing industry , Technology , University/Research institute