Practical 1

 Practical 1: What was done and how it was done.

Objective:

There were 4  objectives done in this practical. The first objective was to identify the parts BD100®. The second was to explain the function of each parts, the third is to explain the relationship among the parts and finally determine the heating energy.

Reverse Engineering Procedures:

What the group did was first detach the coffee maker and unscrew the screws to observe what is inside the coffee maker.

Figure 1: Unscrewing of Coffee maker

 Then the group notified and took note of how the water line flows to enable us to understand how the coffee maker heats up the water. 

The group applied a skill that we had learned in our Lab and Process Safety II module last semester which is line tracing in this practical. Although lie tracing is mainly used for pilot plant, it was also useful in this situation to find out where the water travels. The group line traced the electrical line to see how the heating element works.

After the line tracing, the group discovered that there is a part of the coffee maker that has a valve in it and we had to figure out what those valves do and what purpose do they serve.

Figure 2: Check Valve 

We dismantled the valve from coffee maker to make further observation of what they do. After some time, the group discovered that one of the orange tubes contained a check valve in it. With that information, we had to figure out which side to put the check valve on as the tubes have 2 ways. We figured it out by allowing water to flow into the valve to see whether water will flow out. If the water flows out, it signifies that the valve was correctly placed. If there is no water flowing out, this signifies that the valve was placed incorrectly. 

The side that has to have the check valve is the inlet which is the one from the reservoir. We managed to get the correct set-up of the valve. This is to prevent the water in the reservoir to get heated as the check valve prevents the vapor from going back up to the reservoir.

One of the holes lead to one of the tube which leads the water to the reservoir which will go down to the heating element. The heating element is shown below.

Figure 3: Electrical line and heating element 

One of the tubes will take the water from the reservoir which will circle around and then goes to the outlet. While it is circling around, it comes into contact with the heating element thus heating up the water in the process.

On the diagram below, the one connected to the electrical wire is the one that heats up as it is connected to the heating source. The smaller one touches the inner side of the big tube therefore it only heats up that side of the tube. This is called localized heating.

Eventually, when we were done observing and deducing what each component does, we reassembled the parts back together and screwed back the screws that was initially removed.

Determination of Energy Consumption:

In order to determine the energy consumption, the group had to see the the coffee maker in action. So we made our own coffee and took the measurements needed. Now how did we make the coffee? It was quite simple. The group poured water in the compartment as shown in the image below.

Figure 4: Place to Pour Water

While we were making the coffee, we were asked how does the water go up back the outlet to make the coffee when the heating element is at the bottom and there is no pump in the coffee maker. That is when we learnt something called air-lift pump. This is due to the hot water having low density which causes the water to rise up without the pump as the water vapor will carry the water up.

Before all that, we had to measure some mass of items given to us. First the group measured the mass of dry coffee filter paper and mass of coffee powder used using a weighing scale. Second was to measure the volume of the water used. Third was to measure the surrounding temperature (room temperature) and the average temperature of the coffee powder before it was put in the machine. and finally was the temperature of the water used.

With all that measured we proceeded to make our coffee. As the coffee was being made, the group took notice of the time for the coffee to be brewed. When the coffee was finish brewing, the group measured the mass of the wet coffee filter and the spent coffee powder, volume of the brewed coffee and the mass of the brewed coffee. The final temperature of the brewed coffee was also taken. Since there was condensate on the lid, that also has to be taken into consideration. Material balance was used in order to find the mass of the condensate on the lid. 

Figure 5: Condensate on the Lid 

As seen on the image, there are condensate on the lid.

With the information the group measured, the approximate energy needed for each component can be measured.

The power of the measured in an interval of 1 min for 3 min to find the average power usage of the coffee maker and eventually find the average energy. The tool used to measure the power is called electricity consumption monitor and is show below. The coffee maker had to be plugged in in order for there to have a reading.

Figure 6: Electricity Consumption Monitor 

When all the measurements have been taken, it was time for house keeping. We allowed the coffee maker to cool down for 5 to 10 minutes first. When 5-10 minutes have passed, the group cleaned the outside of the coffee maker using a moist cloth and remove the detachable components such as the filter holder, permanent filter, water tank, cover and jug. The filter and spent coffee was disposed into the waste bin. 

The group then cleaned the detachable components using a dishwashing liquid followed by rinsing the components through tap water. The group then reassembled back the detachable components into the coffee maker. When all groups were done, there was a small debrief and everyone went home to proceed with the report.