Development of Cold Energy Transport System Unilizing Ice/Water Mixture for District Cooling

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1. The ice/water mixture transportation system was designed taking social conditions such as the electric charge system into consideration.2. The characteristics of ice/water mixture through pipes were investigated. Effects of pipe diameter, pipe material and particle size on the pressure drop through a straight pipe were clarified, and a method to predict the pressure drop was proposed taking these factors into consideration. The energy loss and ice distribution characteristics in branching pipes were clarified experimentally. Compressive yield stress of an ice-particle cluster in water was measured. The yield stress thus obtained was shown to correspond with the adhesive property of particles to form clusters in a pipe flow.3. A device was developed to control the flow rate and the ice fraction in a pipe branching from the main transportation pipe. This device was confirmed to work successfully irrespective of the flow condition in the main pipe.4. Blockage at a vertical downward pipe connected to a horizontal pipe with an elbow and an ice fraction regulator wsa investigated. The compressed-plug type blockage occurred at the latter when the ice concentration ratio exceeded a critical value which depended on particle shape/size.5. A storage tank was made on a trial basis. Tests on the performance of the device to take out ice to the main pipe were carried out to obtain data for further improvement.6. Heat transfer characteristics of ice/water mixture flow in the double piped heat exchanger was investigated. Relationship between heat transfer coefficient and velocity or ice fraction was clarified.7. An ice-water direct contact heat exchanger was contrived and heat transfer characteristics between ice and water in the heat exchanger were studied. Effects of velocity on the heat transfer coefficient and amount of ice necessary to attain a desired heat exchange rate were clarified.