ABSTRACT
Evaporative cooling technology has been widely used in industry especially in
evaporative cooler. The evaporative cooler is also called closed cooling tower when the
inside working fluid is water. Its operating principle is that the cooled fluid flow in the
inside of heat exchanger which is sprayed with water outside,then the flow fluid inside
exchange heat with the sprayed water outside,finally,the exchange heat between sprayed
water and air is emitted into the atmosphere by draft fan. This paper is focus on three
aspects, research on the air pressure drop properties of the evaporative cooler and
conductive plastic pipe applied in the evaporative cooler, test on conductive coefficient
and antifreezing test of plastic pipe. These work play an active role in understanding
design factors of air resistance of evaporative cooler and exploring antifreezing
resistance, scale, anti-corrosion of new type of pipe applied in evaporative cooler
especially in closed cooling tower.
This paper analyzes air flow characteristics outside the pipe bundles and resistance
empirical formula, and improve the test-bed of air pressure drop of closed cooling tower.
Compare air pressure drop when coil is in hot and cold state. The results show that:the
coil state have little effect on air drop of the outside tubes in the test temperature.The
effect of coil state can be ignored when refer to empirical calculation formula of air
drop.
Conductivity of plastic pipe is measured by the method of steady-state heat
conduction, and antifreezing resistance of plastic pipe is tested too. The results show
that:the antifreezing test of plastic pipe is good in test temperature although the pipe
have little micro plastic deformation,which provide the information that it is a good
solution to solve the problem of frost cracking of coil during the winter.
Analyze feasibility of conductive plastic pipe applied in closed cooling tower
theoretically,then explain tech-economic rationality of conductive plastic pipe as its
conductivity meet the requirement. Compare heat transfer performance of conductive
plastic pipe and high-density PE pipe in the test.Finally, heat transfer performance of
conductive plastic pipe tested and theoretical heat transfer performance of copper were
compared. The results show that: heat transfer performance of conductive plastic pipe is
better than high-density PE pipe. As conductivity of plastic pipe is low,the relevant
volume of closed cooling tower is larger than the one of metal coil. In order to control
the volume and cost of closed cooling tower under the same heat transfer performance,