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ChaiBrew

Automatically Brew an Authentic Masala Chai Latte, a product development build

 
 
An authentic cup of masala chai tea will have assam tea with heated milk and a multitude of spices!

An authentic cup of masala chai tea will have assam tea with heated milk and a multitude of spices!

 
Our prototype all completed and working properly!

Our prototype all completed and working properly!

 

Initial ideas

The original idea from the entrepreneurs that have asked us to create this prototype for them was to have a completely automatic chai latte brewer. In this model, the amount of tea/spices/water/milk were housed within the brewer itself and were automatically dispensed based on dials/settings set by the user. 

A team before us had made a prototype V1 that was able to do the above but had a multitude of issues such as being hard to clean, non-adjustable to user settings, and having too many moving parts.

However, later on, this approach was changed to have the user physically put in their desired amounts in then "set it and forget it" until their tea is done.

My role was to look into water/milk dispensing, heating elements, brew times, and food safety codes for appliances.  I did taste comparisons between authentic chai lattes brewed by the sponsors and the lattes that our prototype made. I was also the project manager and set soft/hard deadlines for the components within the project.

 

 

Traditional Chai Latte Method

  1. Water and spices is added to a small pot and brought to boil

  2. Tea and milk is added to the pot

  3. The mixture is brought to a boil again so that the tea properly steeps for 2-3 minutes

  4. Mixture is strained into a cup

  5. Ready to be served!

ChaiBrew Machine Method

  1. Water is added to water container

  2. Tea and spices are added to brewing container

  3. Milk is added to glass kettle

  4. When the water is at steeping temperature, it dispenses into the brewing container

  5. Milk is warmed by heater underneath kettle, stir bar continuously stirs milk in kettle

  6. Tea is dispensed after 3 minutes of brewing and strained into the kettle with the warmed milk

  7. Ready to be served!

 

Frame

  • Adapted from a usual 12-cup drip coffee maker

  • Stainless steel brewing container replaces plastic brewing basket that usually comes with coffee maker

  • does not melt when attached to heating pads

Base box

  • allows space for stirring motor

  • widened to comply with UL tipping standards (attached brackets to widen base)

    • Tipping standard: must be able to right itself when leaned to any side at a 45° angle

    • Following UL-1082

 

Immersion Heater

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

Flow-through Heater

  • found in usual coffee makers

  • heats water to 95°C for brewing container from preheated water

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

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 at temperature and will not lose heat to container or ingredients

 

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

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

 

Electronic Components

  • Three solid state relays

    • all heaters connected to relays so that they can be controlled by arduino

  • Arduino Uno

    • controls all three heaters, stirring motor, and solenoid

  • MOSFETs

    • allows control of solenoid and motor through arduino

  • 50㏀ Resistor

    • ensures that even though there may be spikes in voltage, motor and solenoid do not erratically turn on

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