Roberto Silva #65330 February 13,2016 Prof. Eduardo Cabrera

 Objective  Introduction  Procedure  Results  Discussion  Conclusion  Recommendations

 The objective of this experiment is to characterize heat transfer in several kind of heat exchangers like plate, shell and tube and concentric heat exchanger.

 A heat exchanger is an equipment in which transfers heat between surfaces or fluids. The main observation that can be done by working with heat exchangers is that a fluid enters at a temperature and exits at another temperature. This has many common utilities in the industries for example a chiller has its own shell and tube system to be able to lower the temperature of the water in order for a chiller system to provide cold air. There are also other types of uses for heat exchanger where we want to heat a fluid. For this experiment we were able to see cross flow and parallel flow configurations and see how they work.

 Turn on the main switch and set the temperature to the desired temperature then turn on the water heater and wait to get to the desired temperature.  This experiment will be with different temperatures ranging from 40 to 60 degrees.  Set the flow indicator from hot to cold and vise versa when adjusting the flow control valve to the desired flow of the observation.  The range of the flow is from 1 to 2.5 liter per minute.  This experiment will flow concurrent and countercurrent setups.  The table will tell you the temperature of the hot water, the flow of the cold and hot water and when it is counter or concurrent.  Repeat these steps with the three types of heat Exchangers(shell and tube, concentric and plate).

Table 3.7 Overall Heat Transfer Coerfficient Obs. Mass Flow rate ṁ hot (kg/s) Mass Flow rate ṁ cold (kg/s) Heat Rate Delivered Q hot (W) ΔT ln U

 In this experiment we take the data of two kinds of heat exchanger to make some calculations and then obtain efficiency, heat flow rates, temperatures differentials and other complete other necessary calculations needed. The objective of this experiment is to characterize heat transfer in several kind of heat exchangers like plate and shell and tube heat exchanger.  The first experiment was with the shell and tube heat exchanger to complete the table of data and obtain efficiency, heat flow rates, temperatures differentials and other complete other necessary calculations needed to complete the experiment. As the theory establish in the countercurrent flow the system is more efficient because the fluid enter the heat exchanger in opposite direction and this way is how the system can transfer the most of heat.  By observing the Overall Efficiency Calculation (Table 3.5), it can be noticeable the behavior of change in T H and change in T C. When the flow rate of the cold water increased, change in T C decreased and change in T H increased. This expected behavior can be explained by referring to the energy balance equation; (m cp ΔT ) Hot = (m cp ΔT ) Cold.  In the plate heat exchanger results we had higher efficiency than shell and tube like in the theory. When the temperature was settled to be 50 Celsius with cold flow rate high and hot flow rate low liters per minute the system was able to achieve almost 15 degrees in change. With shell and tube only was a couple of degrees difference

 By concluding this experiment it can be demonstrated that basic law of thermodynamics principals were successfully met. The main objective for this experiment was to analyze two different heat exchangers and compare them changing their temperatures and mass flow. These calculations were done in order to obtain their efficiencies and demonstrated if having the flow on parallel or in counter flow will be more effective. The counter flow was the most effective way to exchange the heat, this have logic because as the hot water move it founds colder water in the other side of the tube and vise versa. In parallel flow it continues parallel to the other water and they will be closer to find equilibrium. In terms of efficiency the highest efficiency was 200% but that's to high to be real and then the best was 94.68%.

 For this experiment will be interesting if we were able to compare between the cooled by air heat exchangers and the cooled by water ones and have a bigger difference temperatures or bigger heat exchangers to have more notable changes.