Experimental Study of Cooling Tower Packing and Deduce the New Formula of the NTU

As the main heat exchanger for cooling tower, the performance of cooling tower packing will directly affect the cooling effect of the cooling tower. So it is important to develop the new cooling tower packing and test the performance. In this paper, the empirical formula of the new ramp-type packing was deduced based on an experimental study of packing performance. And the author analyse the factor affecting the number of transfer units(NTU) find that the NTU is not only related to gas-water ratio. According to the experimental study, the author deduced the new formula of the NTU and verified that the new formula of NTU is more accurate than the traditional formula Within a certain range of parameters.

New Approach to Determine the Heat+transfer Coefficients for Cooling Tower Packing

The heat input response technique was developed to determine the heat-transfer coefficients for a forced draught cooling tower packing. The method was applied to a counter current type air-water contact system in a packed bed. A temperature change was alternately imposed on inlet air at the tower bottom and on inlet water at the tower top. Outlet temperatures of air and water were measured with time. From zeroth moments of these temperature changes, water-film and air-film heat-transfer coefficients have been estimated. Finally, the effect of the water/air loading ratio and the packing material, such as wood, aluminium wire netting and plastic PVC on the values of the heat-transfer coefficients was experimentally tested. An empirical relationship between the gas-side heat-transfer coefficient, liquid-side heat-transfer coefficient and water/gas ratio has been established within the range of the tested data.