Russell Peterson, Sean Brown, and Dr. Randy Lewis, Chemical Engineering
Introduction
During his travels to Porcon, Peru, Dr. Randy Lewis took note of how the locals wanted to improve their living situations. One request was for hot water in their main restaurant, “Jesus Pan de Vida.” Hot water was already present in Porcon’s tourist venues and hotels; however, the locals could not spare the cost of electric water heating for their own personal use. Our proposal was to build an inexpensive, maintainable, and safe water heating system. Electric heating systems cost roughly $550 in addition to the cost to run the system. The material cost for our proposed solution, as purchased in Peru, was $220, with no additional operational costs.
Methodology
After speaking with a local representative several times a week, we settled on using waste heat from their existing furnace to heat the water for their system. We built a duplicate furnace in Provo, Utah, which enabled us to experiment with different size pipes and system architectures. Figure 1 shows the heating and cooling treads of three different size pipes (‘:h”, %”, and 1 “) in three different positions (front, middle, and back of furnace) for one trial. This type of test was repeated and randomized according to statistical practices.
From our initial testing, we selected %” copper pipe because of its quick response time.
Our overall system design may be found in Figure 2. This design uses a dual tank system: tank 1 actively heats the water while tank 2 stores the water until use. In this system, cold water in tank 1 sinks into the copper pipes. As the water’s temperatures increases and the density decreases, buoyancy forces cause the hot water to exit the copper pipes into the top of tank 1. This natural convection continues until the surface temperature of tank 1 reaches 160°F, the thermostat’s rated temperature, in which the thermostat opens and drains the hot water into an insulated tank 2. As the water level decreases, a ball cock valve (commonly found in toilets) opens and refills the tank. Hot water is then available from the piping that is tapped into the bottom of tank 2.
Results
We traveled to Porcon on April 29th to implement this system. Originally we had designed the system to be built on the inside of the restaurant, with the copper pipes protruding out of the sides of the furnace. However, when we arrived, we learned that the owner and cooks of the restaurant required there to be no evidence of the system inside of the restaurant. As a result we redesigned the system to be outside with the pipes entering the restaurant through the back of the furnace. Figure 3 shows a CAD rendering of the design as implemented in Peru.
Several hurdles were overcome to make this implementation possible. The locals played an integral part in solving these problems. On May 2nd we had our first initial testing of the system, which proved to be an enormous success. Figure 4 shows the first stream of hot water coming out through the modified faucets we engineered. On May 3rd we refined the system and wrapped the lines and tanks in insulation. Figure 5 shows the final project as it stands in Porcon.
Discussion & Conclusion
Throughout the implementation process, we learned that the local cooks use the high pressure from the water to clean the plates. Unfortunately the hot water line only has pressure equal to the gravitational pull between the faucet and the tank. Future global engineering outreach students could increase the height of the tanks and thereby increase the pressure. The project, however, met our proposed specifications by being less than $220 and was equipped with several safety features: such as a constant temperature thermostat and overflow drains.