Final Design

ChaiBrew Machine Prototype #2

Through all of our hard work, we present the the final design of the ChaiBrew Machine, second prototype.

Figure 2: Schematic of ChaiBrew Machine

Heating Components

• • Immersion Heater

    • preheats water to 70°C so that final steeping temperature can be around 95°C

Figure 3: Immersion heater in water container (left)

Usual immersion heater (right)

• • Flow-through Heater (found in usual coffee makers)

    • heats water to 95°C for brewing container by taking preheated

    • placed below metal plate that kettle is on, therefore simultaneously heats up milk

Figure 4: Horseshoe-shaped flow-through heater on the bottom of the coffee maker

• • Heating Pads

  • surrounds brewing container to maintain steeping temperature of 95°C

  • turns on before the water is dispensed in so that the container and ingredients are already warm as well

    • so that water will not lose heat to container and ingredients

Figure 5: Heating Pad area with (left) and without (right) metal brewing container

Magnetic Stirring

Prevents milk from boiling over, mixes milk and tea

• • Motor with magnets

    • Magnets are attached to rotating rod on motor

    • attached to the base of the coffee maker frame and resides in the steel base box

  • Magnetic stir bar

    • strong magnets press fitted into a machined aluminum cylinder

  • Food-grade silicone ring in kettle

    • prevents stir bar from straying from the middle and being attracted to the ferrous material in the flow-through heater beneath the metal plate

  • Aluminum plate

  • replaces steel plate to allow stir bar to move and not just stick to the plate

Figure 5: Magnetic stir bar in glass kettle

Figure 6: Stirring assembly shown with motor and stir bar

Figure 7: Aluminum Rod with strong magnets inside

Valve Opener

• • Solenoid connected to metal arm

  • 12 volt solenoid

  • controlled through a MOSFET and Arduino

• Presses onto valve after steeping time of 3 min to dispense tea

• Prevents over steeping

• Valve taken from original coffee maker

Figure 10: Actual circuit of product

Controls/Code

• • Closed Loop Control

    • Temperature sensor to turn on flow-through heater after temperature in water container hits 70°C

    • Immersion heater turns off after

  • Open Loop Control

    • Time-based control for heating pads and solenoid

  • Always on

  • Magnetic stirrer is constantly on when switch on coffee maker is pushed

• Please Refer to the Programs/Code section for all of the arduino code used