Armfield UOP8-MKII-Tray Drier

Name of the equipment

Brand

Armfield UOP8-MKII-A

Description

Armfield UOP8-MKII Tray Drier is a small-scale benchtop tray dryer that dries solids by passing a stream of hot air over trays of wet material, a method commonly used in industry. It comprises a square air duct fabricated from stainless steel. Air is drawn into the duct through a mesh guard and flow damper by an axial flow fan. The fan speed can be controlled to produce a range of air velocities in the duct. The air passes over an electrically heated element with electronic closed-loop control, which provides stable air temperatures at the user-selected value. A tray carrier is located in the central section of the duct, which can hold up to three trays of material to be dried. The trays are made with three lightweight coated aluminium and are suitable for food applications. The trays are inserted or removed from the duct through a latched side door with an acrylic panel for viewing purposes. The total weight of the trays and the carrier is measured using three load cells and is displayed on the software. A graph of weight against time allows the drying regimes to be displayed and understood. From the rate of change (slope) of this graph the drying rate can be determined.

Comprehensive instrumentation is included and the measured values recorded on the computer:

Weight of trays plus contents (with tare function)
Temperature (dry bulb) and relative humidity of the heated air before the trays
Temperature and relative humidity of the air after passing over the trays
Air velocity

From each pair of temperature and relative humidity readings the full thermodynamic properties of the air can be determined using a psychrometric chart, i.e. the wet bulb temperature, the moisture content and the changes in enthalpy. This allows for a more in-depth analysis for project or research work, for example comparing the change in moisture content of the air with the rate of moisture loss from the trays.

Specification

Computer control of temperature and air flow rate, with sophisticated data logging and analysis software
Capacity: up to 2.1kg of wet material
Flow rates 0.4 to 3.0 m/s over trays
Temperatures up to 80°C at 0.4 m/s (less at higher flows)
Integrated electronic weight measurement to determine drying rate
Electronic measurement of temperature and humidity before and after the drying trays
Electronic measurement of air flow

Applications

It is applicable to the unit operations laboratory and also to food technology education and research. This instrument able to demonstrate:

Drying rate regimes
Heat and mass transfer
Drying tests on solids for industrial use
Effect of temperature and air velocity on drying rates
Use of psychrometric charts

Contact information

Equipment-in-charge: Miss Fung Lok Wan, Lolita

Email: lok-wan.fung@polyu.edu.hk

Office: TU305