Particle size distribution in ice slurry systems: setup and analysis.

Ice slurry is used as secondary refrigerant and for energy storage. It is a mixture of water, a freezing point depressant and small ice particles. The usage of ice slurry can reduce the exergy losses of a cooling system and the refrigeration charge in the primary system. It is possible to uncouple the cooling demand from the cold production of refrigeration systems. Due to the latent heat of fusion of the small ice particles in the liquid phase, ice slurry has a high energy compared to single phase systems.
Important parameters influencing the thermophysical and rheological properties of ice slurry are the ice particle size and the size distribution as well as the shape and surface characteristics of the ice particles.
Some prospective investigations have been published. The most practical way to observe the ice particles is by using a microscope. The possibility of non-symmetrical and flat particles orientated in same direction is a possible error of this method due to the two dimensional measurement and the floating of the particles. It cannot be determined by a two-dimensional method. Based on the basic microscopic observation a new method of measuring the ice particles had been developed. In order to measure the size of the particles in more than one observation plane a special concept is shown. A small square transparent channel is used to separate the particles. The simultaneous measurement of two observation planes could be realized by using two small mir-ror planes. The special lightning is directed in two orthogonal planes through these square channels. A micro-scope with digital camera is used to observe the two observation planes simultaneously.
The images are processed in MATLAB and the particles are separated in binary images for analysis. First tests with a smaller flow channel show good results for the method.
It can be shown that it is possible to observe the ice particles with the enhanced method on more than one observation plane.