What is Refrigerator

Prior to the invention of refrigerators, food preservation imposed serious constraints. The best options were to suspend food in rivers, wells, or at the bottom of lakes, and absent these tactics, stable foods were heavily salted, spiced, pickled, or dried to prevent bacterial growth. With the industrial age, we began to understand thermodynamic cycles and—through an interplay of pumps, valves, and heat exchange—learned to cool food to arbitrary temperatures with the refrigerator cycle. We just saw that the refrigerator carries out a cycle to move heat out from the food compartment and into the room. This occurs via three main components: A pump that compresses gas. A valve that expands gas. Radiators that allow gas to exchange heat with the …

Why does not Aircraft Cabin Pressurized as Ground Level

Have you got your ear numb when you’re moving from one altitude to another one? It may happen when you use high elevator or mostly when you’re inside a takeoff or landing aircraft. In normal circumstances the air pressure is the same on both sides of our eardrums. But when the pressure in our environment changes significantly, the pressure on the outside of the eardrum is no longer the same as that on the inside. This pressure difference is eventually regulated by the Eustachian tube, a sort of air canal that links the middle ear to the back of the throat. If your eardrum can’t take the pressure difference, It will do the same as a balloon will blown up when it fly too high. …

How Tree Got Its Masses

Tress is one of the biggest thing that take place on our earth. Ever thinking how the tress in front of your house become so big and have a massive mass? Where are the mass come from? Put it in your mind and try to find it ! As Antoine Lavoisier said that mass in a closed system will be always has a same amount, so with the trees! In early 1960’s, a scientist Jan Baptist van Helmont try to figure out where the mass on tree is coming from. He make an experiment by measure a mass of soil and planted a plant over it. After take care the tree over 5 year, he pull it off and measure the soil’s mass. He found that the …

VA vs Watt

You may see power unit that written as KVA and KW. Can you guess which one is true? The answer lead to both of them are true. KW will have the same meaning as KVA when the KVAR component is 0. Thinking as a perpendicular triangle with KW and KVAR as its perpendicular side and KVA as its hypotenuse. So when the devices came into a motor, it will had KVAR unit and for simplifying it we can write it as KVAR with pF (power factor). KVA is more likely a sum of KVAR and KW. It also happened with generator or our electricity provider. They’re written in KVA that means whatever is our load, it can handle up to …

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