Prototype
Evaluation
Analysis of the Teapot Heat Retention
Heat retention as defined for the purposes of this analysis: fall in temperature (degrees C) in period, P, of 4 minutes.
P = 5 min - Estimated maximum brewing time.
Modeling Heat Retention:
Equipment: Teapot, Infuser, Lid, Termometer, Measuring Cup, Kettle.
Material: Tap water
Hypothesis: Teapot is good if it doesn't allow a drop in temperature of more than 5 degrees in 5 mins, if the starting point is 90 degrees C.
Justification:
Teas and brewing details:
White tea 65 to 70 °C (149 to 158 °F) 1–2 minutes
Yellow tea 70 to 75 °C (158 to 167 °F) 1–2 minutes
Green tea 75 to 80 °C (167 to 176 °F) 1–2 minutes
Oolong tea 80 to 85 °C (176 to 185 °F) 2–3 minutes
Black tea 99 °C (210 °F) 2–3 minutes
http://en.wikipedia.org/wiki/Tea#Preparation
From the table above, most teas allow for a temperature drop of 5 degrees C. Also the maximum brewing time is 3 minutes.
Having in mind that the experiment is done with water and not tea, and that this means that heat loss measured under these circumstances would be less than the that of actual tea (due to heat being transmitted to tea leaves) the time that the teapot has to keep the heat in is 5 instead of 3 minutes.
H0: The water in teapot will drop in temperature for more than 5.5 degrees in 5 minutes
Process: I boiled 1 l of water in the kettle and poured 0,5 l (500 ml) into the measuring cup and then teapot.
I was doing the measurements with the infuser inside the teapot and the lid on top, to make it as similar as possible to the conditions that will be present when teapot is used for making tea.
When the temperature of the water reached 90 degrees, measurements of temperature were taken on every full minute for the next 5 minutes.
The whole process was repeated 5 times and the results are shown on the graph below.
P = 5 min - Estimated maximum brewing time.
Modeling Heat Retention:
Equipment: Teapot, Infuser, Lid, Termometer, Measuring Cup, Kettle.
Material: Tap water
Hypothesis: Teapot is good if it doesn't allow a drop in temperature of more than 5 degrees in 5 mins, if the starting point is 90 degrees C.
Justification:
Teas and brewing details:
White tea 65 to 70 °C (149 to 158 °F) 1–2 minutes
Yellow tea 70 to 75 °C (158 to 167 °F) 1–2 minutes
Green tea 75 to 80 °C (167 to 176 °F) 1–2 minutes
Oolong tea 80 to 85 °C (176 to 185 °F) 2–3 minutes
Black tea 99 °C (210 °F) 2–3 minutes
http://en.wikipedia.org/wiki/Tea#Preparation
From the table above, most teas allow for a temperature drop of 5 degrees C. Also the maximum brewing time is 3 minutes.
Having in mind that the experiment is done with water and not tea, and that this means that heat loss measured under these circumstances would be less than the that of actual tea (due to heat being transmitted to tea leaves) the time that the teapot has to keep the heat in is 5 instead of 3 minutes.
H0: The water in teapot will drop in temperature for more than 5.5 degrees in 5 minutes
Process: I boiled 1 l of water in the kettle and poured 0,5 l (500 ml) into the measuring cup and then teapot.
I was doing the measurements with the infuser inside the teapot and the lid on top, to make it as similar as possible to the conditions that will be present when teapot is used for making tea.
When the temperature of the water reached 90 degrees, measurements of temperature were taken on every full minute for the next 5 minutes.
The whole process was repeated 5 times and the results are shown on the graph below.
Conclusion:
The average end point temperature after 5 measurements was 85.02 degrees C. This means that on average, the teapot can keep the temperature from falling beyond 90 - 5.5 = 84.5 °C .
This means that we can reject the H0 and that the prototype has passed the heat retention evaluation.
Sources of error:
1. The lid is not closed in the same manner every time - the thermometer does not allow it to close fully.
2. Starting teapot temperatures are different for different measurements.
The average end point temperature after 5 measurements was 85.02 degrees C. This means that on average, the teapot can keep the temperature from falling beyond 90 - 5.5 = 84.5 °C .
This means that we can reject the H0 and that the prototype has passed the heat retention evaluation.
Sources of error:
1. The lid is not closed in the same manner every time - the thermometer does not allow it to close fully.
2. Starting teapot temperatures are different for different measurements.