Univ. of Maryland and Marquette Univ. Develop Energy-Efficient Appliance Concepts
The U.S. Department of Energy loves to sponsor academic competitions, trying to stimulate college and university students’ minds into creating a greener, more energy-efficient tomorrow with product concepts that one day could be implemented by major manufacturers and companies.
The future was on display at the recently completed Max Tech and Beyond Appliance Design Competition. The competition was a joint effort between the DOE, the Lawrence Berkeley National Laboratory Energy Efficiency Standards Group, the U.S. Office of Energy Efficiency and Renewable Energy and the U.S. Building Technologies Program.
The challenge for the 20 schools whose initial proposals were accepted was to design and test appliance innovations that have the potential to significantly reduce energy consumption while providing a level of performance that is comparable to or better than current products.
The schools rose to the challenge, and the University of Maryland at College Park was declared the winner two weeks ago, for its innovative air-conditioning design that would greatly reduce the amount of energy use, while Marquette University took the runner-up spot for its creation of a hybrid appliance that both heats water and dries clothes at the same time while increasing efficiency.
Fascinating in their creation, both projects are worth a closer look and may see commercialization one day.
The Univ. of Maryland team found a way to remove humidity without using more energy. The winning team, comprised of graduate and undergrad students and led by Dr. Yunho Hwang, decided early on that when attacking energy efficiency, an air-conditioner was an easy place to start.
“It’s the largest consumer of electricity in houses, so we thought it was an easy place for us to pick at it and see if those of us who are strong in energy sciences can figure something out,” says Michael Siemann, the student lead on the project.
The Univ. of Maryland team focused first on creating a desiccant system to remove humidity. Siemann explains in layman’s terms: “If you want your house to be at 70 degrees, the cool air coming out has to be lower than the dew point; your dew point will be in the 50s. The colder you want the air, the bigger compressor you have, which, of course, means the more energy you’re going to be using.”
So the Univ. of Maryland group thought about using a separate system to remove humidity, but unlike other systems like that had attempted this before, the team wanted to do it without using additional energy. Suxin Qian, another student on the team, says the group also wanted to make sure the system was small enough that consumers would be able to install it in their homes; the early designs, Qian says, were huge.
Eventually, the Maryland team made a breakthrough. It was able to design a system that took the energy that the air-conditioner was dumping to the outside as hot air and reuse it to recharge the system that removes the humidity from the air.
“Since we don’t have to remove the humidity with the vapor compression cycle, you can get a smaller compressor to provide the cooling down,” Siemann says. “So you’re attacking from both sides: you’re removing waste and reducing energy.”
The prototype costs about $2,000, Siemann says. But the Maryland team’s ability to create separate systems for sensible and latent heat cooling, and in its tests show a 30-percent energy savings, was greatly due to a new Mitsubishi desiccant material, the FAM-ZO1.
The new desiccant regenerates more efficiently in the temperature ranges that the condenser could produce than what was previously available, Siemann explains. “Basically, it allowed us to run a split sensible/latent system most efficiently without an added heat source,” he says.
The project is expected to be shown to a consortium of air-conditioner manufacturers this fall. Siemann says, however, no one on the team is looking to get rich off the design.
“I’d just be happy if there were better, more efficient air-conditioners in the world,” he says.
Marquette’s Water Heater-Clothes Dryer
At Marquette University, two different teams assembled by faculty members Jon Koch and Phil Vogelwede tackled the challenge of making a more energy-efficient appliance by combining two appliances: a water heater and a clothes dryer. The Marquette team wanted to build a machine that would use the waste heat from a clothes dryer to heat water for the next wash load.
“We settled on the gas-burner idea because normally, the burners run for an hour a day, so why not make something that has one burner and make it work for two appliances at once?” Koch explains.
Wade Loofboro, a graduate student at the school, says the project appealed to him as “innovative and really challenging.”
“Clothes dryers haven’t been regulated by the Energy Star program, and I think that what we saw with water extraction, there was a huge potential to get water out more efficiently,” he says. “And with the whole idea of storage tank water heaters, we knew there were great strides being made in terms of efficiency but that they were coming at great cost.”
The Marquette team designed a prototype (see graphic above) that began with a clothes dryer atop a custom-built storage-style water heater tank that fit within the standard dimensions of washers and dryers. The water storage tank encloses a combustion chamber, while the dryer houses a fan. Each unit is utilized by both appliances.
In the water heater mode, an 8-hour test done by the students resulted in a calculated energy factor of 0.83, exceeding the benchmark of 0.70. The first-hour hot water delivery was measured to be 70 gallons — competitive with that of a typical storage water heater. In dryer mode, the efficiency for a 12-pound dry load with 10 pounds of added water was measured to be only 26 percent, falling short of the 54-percent benchmark the group had set.
Most of this shortcoming, Koch explains, was due to the heat loss from the combustion chamber to the water, which is unwanted in clothes-drying mode; however, the team’s research indicated that an improved combustor design could enable the hybrid device to achieve the benchmark dryer efficiency.
“We thought it was a simple idea, taking one exhaust waste from the other, but it turned out to be more complicated,” says Jason Gaska, another student who worked on the project. “One issue we had was managing the different temperatures of the exhaust product and heating it up to the same temperature that people run their water heater.”
Koch says the team’s design, which costs $5,100, interested some appliance manufacturers that were contacted, but “they want to see us improve it; they want to see version 2.0.”
Both respective designs from the Univ. of Maryland and Marquette Univ. may be years away from hitting retail stores, but each found an existing energy inefficiency and worked on a way to improve it, which is something all appliance manufacturers strive for today.