for iced tea enthusiasts Unaided iced tea takes hours to make Brew 28 minutes Cool 26 hours Market for specialized kitchen tools Brew directly into ice Functionality Fill pitcher with ice ID: 372704
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Slide1
Design of a Rapid Beverage Chiller
for iced tea enthusiastsSlide2
Unaided, iced tea takes hours to make
Brew: 2-8 minutes
Cool: 2-6 hoursSlide3
Market for specialized kitchen toolsSlide4
Brew directly into ice
Functionality:
Fill pitcher with ice
Brews tea
Pours tea into pitcherIssues:Hot tea melts iceIce dilutes tea“That freezer taste”Slide5
Ice water circulation
Functionality:
Add ice and water
Insert can or bottleRotates container, sprays with ice waterIssues:
Requires ice (minor)Bad for tea (fixable?)Slide6
Cool new technology: TEC’s
Pros:
Super compact, light
No moving partsCons:Inefficient (40-70%)
(≈300% for full-size fridge)Slide7
Ice versus price
Isolated-ice systems
Pros:
More inexpensive
Likely more compactCons:
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 powerGives off a lot of heatSlide8
Rapid Beverage Cooler: Take 1
Vessel + sensor
Heatsink
Fan
Stirrer
Spigot
TECSlide9
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 Slide10
Rapid Beverage Cooler: Take 2
Three-state process:
Upper fans on, TEC off: Cool to ≈60°C
All fans on, TEC on: Cool to room temp.
Lower fans on, TEC on: Cool to final temp
.Slide11
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 WCalculate the temperature profile:
Aggressive air coolingConstant TEC heat flow: 800W (simplistic)TEC turns on at 60°CSlide12
Cool a liter of tea in 9 minutes
Time elapsed (minutes)
Temperature (°C)Slide13
Problems I may encounter…
Variation in TEC heat transfer rate
Stage 2: Better than estimated
Stage 3: Worse than estimatedHeat dissipation too slow→ Slower cooling process.
Too expensive to mass-produce (>$250?) Backup plan: Investigate other cooling systemsSlide14Slide15
Demand for iced tea chillers
TECs enable powerful, convenient chillers
1 liter: 90°C to 6°C in 9 minutes