Description

The Armfield Computer Controlled Water Cooling Tower has been designed to give students an appreciation of the construction, design and operational characteristics of a modern evaporative cooling system. The unit is also an excellent example of a specialised heat exchanger, where two streams of fluid flow (water and air) are brought into direct contact and in which there is a mass transfer from one phase to the other.

The UOP6-MkII comprises a cooling tower mounted on top of a heated water reservoir. The cooling tower is manufactured from clear acrylic for visibility, and has an easily removable front face to allow different packing materials to be inserted.

Two blocks of different density material and two blocks at reduced height are supplied as standard, but other material can be used for more advanced investigations.

Water is pumped from the reservoir to the top of the tower using a variable speed pump. An array of spray nozzles ensures an even distribution of the water throughout the column section.

As the water descends through the packing material it is cooled by the air flow from the variable speed fan, which blows air upwards through the tower.

Measurements of temperature and RH of the air at the inlet and outlet of the packing allow the change in moisture content of the air to be derived and the mass transfer due to the evaporative cooling to be calculated.

The water is heated by an electrical heater in the sump tank. This can be operated in a closed loop mode to control the water at a specific temperature, or it can be operated at a user defined power (continuously variable across the range) to simulate a fixed load system.

All controls and displays are incorporated in the software supplied with the unit. This can be run on any modern Windows PC (not supplied) and communicates to the hardware using the integral USB interface. From the software it is possible to change the pump and fan speeds, to control the heater and to display all the sensor values.

An optional Packing Characteristics Accessory UOP6-MkII-23 is available. This comprises a divided section of the standard packing, mounted onto a separate column. At three equal distance points within the packing, instrumentation is fitted to measure the water temperature, the air temperature and the RH of the air.

This option is supplied with its own electronic interface module and requires a second USB port on the computer.