Design of a Rapid Beverage Chiller
for iced tea enthusiasts
Unaided, iced tea takes hours to make
Brew: 2-8 minutes Cool: 2-6 hours
Market for specialized kitchen tools
Brew directly into iceFunctionality:• Fill pitcher with ice• Brews tea• Pours tea into pitcher
Issues:• Hot tea melts ice• Ice dilutes tea• “That freezer taste”
Ice water circulationFunctionality:• Add ice and water• Insert can or bottle• Rotates container, sprays
with ice water
Issues:• Requires ice (minor)• Bad for tea (fixable?)
Cool new technology: TEC’s
Pros:• Super compact, light• No moving parts
Cons:• Inefficient (40-70%)
(≈300% for full-size fridge)
Ice versus price
Isolated-ice systems
Pros:• More inexpensive• Likely more compact
Cons:• Needs lots of ice for hot tea
Proposal: TEC-cooled system
Pros:• Plug and play• Precise temperatures
Cons:• Pricier• Bulky (heatsinks!)• Draws a lot of power• Gives off a lot of heat
Rapid Beverage Cooler: Take 1
Vessel + sensor
Heatsink Fan
Stirrer
Spigot
TEC
Design 1: Too hot for TEC operation!
Problem:• Can’t operate past ≈80°C• Not needed at high temps
Solution:• Only run TEC below
certain temperature
Rapid Beverage Cooler: Take 2 Three-state process:
1. Upper fans on, TEC off: Cool to ≈60°C
2. All fans on, TEC on: Cool to room temp.
3. Lower fans on, TEC on: Cool to final temp.
Circuit breaker limits performance• Power from wall: 1500 W (US/Canada)• Power through TEC(s): 1200 W• Breaker is limiting factor (67% efficient TEC):
0.67 × 1500 W × 0.8 = 800 W
Calculate the temperature profile:• Aggressive air cooling• Constant TEC heat flow: 800W (simplistic)• TEC turns on at 60°C
Cool a liter of tea in 9 minutes
2 4 6 8 10
20
40
60
80
100
Time elapsed (minutes)
Tem
pera
ture
(°C)
Problems I may encounter…• Variation in TEC heat transfer rate– Stage 2: Better than estimated– Stage 3: Worse than estimated
• Heat dissipation too slow
→ Slower cooling process.
• Too expensive to mass-produce (>$250?) Backup plan: Investigate other cooling systems
• Demand for iced tea chillers
• TECs enable powerful, convenient chillers
• 1 liter: 90°C to 6°C in 9 minutes