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The Armfield DLMX system is a practical education system aimed at teaching students the basics of fluid mechanics, heat exchange and other fundamental engineering principles. It is a unique combination of coursework and practical demonstration equipment and can be used to teach students of all ages. The equipment comprises a small battery operated base unit, into which one of seven different cartridges is plugged. The base unit contains a water reservoir, pump, controls and viewing panel. The cartridges contain an experimental representation of the topic, and the specific instrumentation required for the particular demonstration. Currently seven different cartridges are available covering fluid mechanics, thermofluids and heat transfer. The cartridges can be changed in seconds as they use a simple plug in mechanism. As the cartridges include their own microcontroller, the base unit automatically detects the cartridge that is fitted and displays the information accordingly. The equipment can be used by a single student, by small groups of students or by a teacher or technician demonstrating to the whole class. The academic content and coursework is provided by Washington State University. It includes classroom exercises, detailed theory of the processes and suggestions for further work. The base unit comprises a clear acrylic water reservoir, mounted on a robust vacuum formed ABS plastic plinth. Under the plinth is a pump with a variable speed control, flow meter, battery, level sensor and the electrical control circuitry with display. The units are battery powered; the internal rechargeable batteries provide more than enough for a long classroom session. The units can also be powered by mains electricity, recharging the batteries at the same time. The simple push fit cartridge interface, provides smartchip and self-sealing hose connections. This mechanism is common to all the DLM cartridges. The quick easy setup ensures that sensible investigations can be performed in less than ten minutes.
Unique and innovative approach to multi-discipline engineering teaching.
This cartridge demonstrates the function of a fan and radiator to cool water. The DLMX reservoir is filled with hot water, which is pumped through the heat exchanger. The inlet and outlet water temperatures are measured to demonstrate the cooling effect. The relationship between heat transfer and water flow rate can also be investigated.
A highly visual demonstration of a fluidised bed. The onset of fluidisation can be demonstrated and the way the height of the bed varies with the flow rate. The pressure drop across the bed is measured, so the way the pressure varies before the onset of fluidisation and after fluidisation has occurred can be illustrated and compared to theory.
The use of an orifice plate to measure flow is demonstrated by measuring the pressure drop across a defined orifice. The geometry of the orifice is in accordance with standard industrial orifice flow meters.
This cartridge requires two DLMX base units, one filled with hot water, and one filled with cold water. The inlet and outlet temperatures of both fluid streams are measured, enabling the heat transfer coefficient to be measured and an energy balance to be performed. The two flow rates can be individually varied and the flow direction through the shell can be easily changed. The internal geometry of the DLM-4 is based on industrial 2-1 shell and tube heat exchangers.
This cartridge requires two DLMX base units, one filled with hot water and one filled with cold water. The inlet and outlet temperatures of both fluid streams are measured, enabling the heat transfer coefficient to be measured and an energy balance to be performed. Reversing the flow in the outer tube demonstrates the difference between co-current and counter-current operation.
This cartridge simultaneously measures the pressure drop across a straight pipe, a smooth bend and a right angle bend. Each test section is of the same cross section and same effective length, enabling meaningful comparisons to be made. The additional energy losses due to the geometry of the flow path can be clearly seen at different flow rates and the relationship to theory can be established.
The DLM-7 demonstrates the Bernoulli equation, showing how low pressure is generated in the throat of a venturi tube, and how this is affected by flow. The flow recovery is also demonstrated by measuring the total pressure drop across the module. The geometry of the venturi orifice is in accordance with standard industrial venturi flow meters, so the use of a venturi to measure flow can also be demonstrated.