![]() ![]() It would initially appear that the pump must overcome the height difference of 10.0M however, due to gravitational effects, this isn’t the case as for every metre of fluid pumped vertically upwards, a corresponding 1.0 M of fluid drops on the return side of the system. The system circulating pump is required to transport the fluid from the bottom of the system (0 M) to the top at 10.0 M. Let’s consider the operating conditions of a closed loop system with an elevation change of say, 10.0 M. Pumps operating in closed loop systems are therefore only required to overcome dynamic friction losses. A closed loop circuit will exhibit only friction losses. Any pump selected for the closed loop system, must be able to transport the fluid to the highest point without flashing or inducing vacuum and the lowest point must also be evaluated for pump shut-off pressure. However, just like open flow systems, we still need to make checks for sufficient NPSHa, that the static pressure throughout the system does not fall below the fluid vapor pressure and therefore induce cavitation etc. One of the unique aspects of closed loop piping systems is that the static elevation is not accounted for in head-pressure calculations as these systems are largely unaffected by static pressure. This is manly the sound the ball makes as it rolls along the track.Figure 1: Closed Loop Fresh Water Cooling Friction is the energy lost as the ball rolls. The ball will have enough KEtop when it starts above a height H=2.5r, neglecting friction that is. This is the force (Fc=mv2/r) needed to keep a mass in a circular motion. ![]() The amount of KEtop needed to keep the ball on the track is equal to the work done by the centripetal force to keep it in the loop. When we star the ball below height H, the initial potential energy is close to equal the potential energy at the top of the loop, so there is not enough kinetic energy left to keep the ball on the track. When the ball reaches height h at the top of the loop, it needs to still have enough kinetic energy to keep it moving around the loop without falling off. ![]() We know from conservation of energy that the work you have done initially in raising the ball equals the initial potential energy which equals the sum of the kinetic and potential energies at any point on the track. What happens to the energy after the ball reaches the bottom of the loop?Īs the ball starts up the side of the loop, the kinetic energy is being converted back into potential energy, so its kinetic energy and its speed decrease. The ball’s potential energy (PE) is being converted into an equal amount of kinetic energy (KE)! At the bottom of the loop, all of the ball’s energy is now kinetic energy. Whatever PEinital you give to the ball will be the total energy the ball has to travel down the track and around the loop since energy cannot be created or destroyed within the system (conservation of energy)! When you release the ball, it begins to fall down the track acquiring a speed, v. The higher the starting height you give the ball, the greater initial potential energy it has. Since the ball is at a greater height, it now has an initial potential energy (PEinital) equal to the work you have done. You are doing work (W) by raising the ball from the table. What happens when you release the ball at other places on the track?Īnswer: The ball only makes it around the loop when it is at height H or higher. ![]() What happens when you release the ball at the upper line?Īnswer: The ball makes it around the loop this time! Now put the ball on the track at a height H above the table (upper line on the track).What do you THINK will happen when you release the ball at the upper line? What happens when you release the ball at the lower line?Īnswer: The ball doesn’t make it around the loop. Put the ball on the track at a height h above the table (lower line on the track).There are two lines on the track for the Loop the Loop, one at a height h (which is twice the radius, r, of the loop) and the other at the larger height H. Kinetic energy (KE)is the energy the object has due to its motion.Ĭonservation of energy states that the total energy of a system remains constant, though it can change forms.Potential energy (PE) is the energy the object has due to its position.Work (W) is the energy given to the object by applying a force over a distance.The three types of energy that we will be considering are: Work, Potential Energy, and Kinetic Energy. The loop the loop is an example of conservation of energy. ![]()
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