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Energy recovery systems aim to recover waste energy that is normally lost to the environment. Waste energy comes in a variety of forms. Many processes involving building HVAC involves transferring energy from one working fluid to another. Governing codes put strict requirements on ventilation requirements for various occupancy types. Increased ventilation demands more from the HVAC equipment since outdoor air (ventilation air) is being brought into the building and requires tempering in order to retain occupant comfort. The energy required to temper this air increases as ventilation rates increase. Many commercial buildings have implemented exhaust air energy recovery, or runaround loops in order to re-capture the energy in the exhaust air streams.
Residential HVAC systems are no different than commercial systems, just less complex typically. There is little being done to recover energy lost in the residential sector. The commercial industry is much further along in energy recovery systems than the residential sector. This is partially due to the lack of interest by home owners. Residential buildings consumed 35% of the total U.S. natural gas consumption in 2008 accounting for more than $90 billion dollars annually. Typical residential furnaces are 80% thermally efficient. The wasted energy is largely found in the combustion products,or flue gasses. By recovering heat from the flue gases, this energy can be reclaimed and put to use.
Having a source for energy recovery is only part of the predicament. A desirable application of the recovered energy is also necessary. Home owners need to see a quick payback as well as an incentive in order to be enticed to make capital investments. Without government aid or tax incentives many individuals lose interest.
This thesis researches using energy recovery from residential gas furnaces to apply reclaimed heat to a radiant driveway heating system. The incentive for this application is the not only a maintenance free driveway in the winter, but reduced costs for snow removal.
Adviser: Haorong Li