Chai Brew

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!

Our prototype all completed and working properly!

Initial ideas

The original idea from the sponsors/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. The brewer itself was a pot similar to the traditional method and one of the biggest pain points was the syringe full of milk. The milk in the syringe and hosing that led to brewer pot would often spoil and be hard to clean.

However, later on, the entrepreneur team adapted the idea 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, integration, brew times, and food safety codes for appliances.  I did all of the physical construction of the prototype so that it was presentable and all moving parts were mounted properly. I also helped with wiring and coding to ensure timing aligned with the best cup of chai. I also did taste comparisons between authentic chai lattes brewed by the sponsors and the lattes that our prototype made. I acted as the project manager and set soft/hard deadlines for the components within the project using gantt charts.

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!

My Role:
I prepared chai the traditional method with good Assam tea so that it could act as our foundation for the flavor that we wanted to achieve. It was a lot of fun to be making good tea in the middle of the night in the engineering labs!

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

My Role:
I gutted a cheap off the shelf Mr.Coffee brewer and was the one to physically mount all the components onto it and also onto the wooden plank for easy transportation as per the sponsor’s request. This being a prototype, the electronics were displayed for easy access, but the intention was that smaller electronics would eventually be used to easily fit into the next iteration.

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 colder container or ingredients

My Role:
I researched different methods of heating water and sourced all additional components/sensors that we would need to modify the coffee brewer to fit our needs. I used food safe silicone caulking to adhere the heating pads to the steeping/brewing area and drilled holds/modified the plastic body of the brewer as necessary.

Magnetic Stirring

Prevents milk from boiling over or creating a “skin” on the surface, mixes milk and tea once tea is dispensed; our reverse engineered version because we did not have the budget and could not wait for the ship time for an affordable magnetic stirrer

• 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

  • custom molded and adhered to glass

• Aluminum plate

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

My Role:
I press fit the magnets into a hollowed aluminum cylinder that my groupmate machined. I molded a ring with our remaining food grade silicone. I created the base box and motor mounts for the magnetized motor beneath the stir 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

My Role:
I mounted the metal arm and solenoid on the 3D printed mount that my groupmates had made. I thoroughly tested to ensure that it triggered properly after the 3 minute steep time.

Electronic Components

• Three solid state relays

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

  • larger than needed relays were used because they shipped within our time constraints

• 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

My Role:
I wired the relays and the MOSFETs to the breadboard. I created the wire diagram so we could understand and track where each component was wired. I adjusted times in the code that my groupmates wrote so we could effectively test for best steep/brew times.