Introduction

In order to know and learn more about what factors would affect the concentration of coffee, we conducted some experiments to test the importance of the proposed factors.

Laboratory 1

The nature of this experiment is to learn if the temperature of the water in common coffee machine is optimized. The optimized temperature for water in making coffee is 92 ⁰C - 96 ⁰C. Below are the findings of this experiment:

Session Picture of The Part Average Water temperature (⁰C) Comment
Water leading tube 78 - 85 The water boiled and rose to the tube in a very quick time. Therefore, the temperature of water is not high enough to make coffee.
Filter holder 80 The water temperature in the filter dropped dramatically since the water in this process would contact with air which would make the water cooled down quickly.
Carafe 75 The water temperature in this part further decreased.

We can conclude that the temperature in the three sessions are not high enough, they cannot reach the optimized temperature. Therefore, with the default elements, it is very difficult for us to make a good coffee.

Laboratory 2

The nature of this experiment is to learn how the temperature affects the concentration of coffee. We tested some water temperatures for making coffee and then tasted by mouth in order to decide the concentration of coffee. The result is shown in the following table: a

Pouring Temperature (⁰C)

Concentration of Coffee

93

5.5

84

5

76

4.5

68

3

Highest number in the column of concentration of coffee means that the coffee is more bitter, vice versa.
a
As the result showed, the temperature is proportional to the concentration of the coffee. If the pouring temperature is higher, the concentration of coffee will be higher. Therefore, we can say that temperature is a very important factor in this project.

Laboratory 3

P1540_30-03-10 The nature of this experiment is to learn the relationship between the immersion time and the concentration of coffee. In this testing, after all the water coming out from the water outlet, we let the water stay in the filter for some time (3, 10, 12, 13, 15, all in seconds). After the specific time, the coffee can then dropping to the carafe. The result is shown in the following table:

Immersion Time (Seconds)

Concentration of Coffee

3

4

10

5

12

6

13

6

15

5.5

Highest number in the column of concentration of coffee means that the coffee is more bitter, vice versa.
a

As the result showed, the immersion time is directly proportional to the concentration of the coffee. Therefore, apart from the temperature, we can say that immersion time is another vital factor. If we let the water stay in the filter longer, the concentration of coffee will be higher. However, if the time of immersion is too long, the texture of coffee will become sour and it is not good to drink. As a result, our group proposed that the immersion time should be between 10 and 15 seconds in order to obtain the best taste of coffee.

Conceptual Design

a Temperature

The first conceptual design was to surrond the water learding tube with a layer of air. The material that we used was a water tube. The reason for doing so is that air is a good insulator, it is hpoed that the heat loss can be reduced. There were two experiments involved in this laboratory, the first one was control experiment; while another was the one that we inserted a water tube.
a
Temperature distribution of the two experimetns

a As the above graph showed, the temperature does not have observable difference between the two experiments. We can say that the temperature rises about 1℃ by the insulation. However, the effect is not large enough. We concluded that this design should not be used if we want to increase the temperature in the drip coffee maker.

The second conceptual design was based on the design 1. We suggested moving the heating unit from the bottom to the top as to skip the cooling from fresh water.

The third one was to prolong the tube with a vertical tube. As the water from the tube to the filter holder cools down for a lot. We suggested covering the water longer and releasing it as long as it reaches the coffee bean. We thought that it can minimize the temperature difference.
The last one was to add an extra cover on the top of the filter. Since large amount of air trapped between the lid and the filter which will make the heat spread out. Add a cover to the reaction between coffee bean and water in a closed area. The temperatures will not lose a lot.
However, after some testing completed by us, we found that the above suggestions were not good enough to increase the temperature in the coffee maker. Therefore, none of them were selected by us in the final design. What we do in order to solve this problem will be revealed later on in this report.


Immersion Time

Ballpoint-pen-parts.jpg The first conceptual design was to place a sensor in the coffee maker. When all the coffee dropping down to the filter, the sensor will serve as a function of counting 10 –15 extra seconds in order to keep the coffee in the filter longer. However, later we thought that it is too complicated and we did not know where to put the sensor.

The second design that we generated was to apply the working mechanism of a ball pen. We all know that ball pen is easy to control, when we press the button, the ink rod will come out. In our design, we suggested using components in the ball pen, when we press the button on the top of the coffee maker, a pin will go down, like the ink rod, and serve as a function of hindering the coffee dropping down to the carafe awhile.

The detailed design of this part will be discussed in the next section.


Design downloaded from free website templates.