GCHP systems are almost always though of as a space heating and cooling technology. As an afterthought they are sometimes considered for water heating domestic hot water. They can do so much more! Heat pumps simply cool and warm air and/or water. What you do with it is limited only by your imagination. Heat pumps and GHX's have been used to...
GCHP's on the farm
GCHP systems are being employed in a wide range of applications. Many systems have been installed in residential applications, mostly homes outside of urban areas, where there is space to install a GHX or connect to a water well. School boards started installing GCHP systems in the 1980's and '90's. The Lincoln County School Board in Nebraska has converted many of their existing schools and all new schools are designed with geothermal systems. Even a 1.5 million square foot (140,000 m2) retail shopping mall is being built with a GCHP pump system. What about applications for the technology in agricultural applications?
A lot of people are familiar with district heating systems. Hot water or steam from a central heating plant is pumped through a network of insulated pipes to nearby buildings. Some district heating systems take advantage of heat produced by a combined heat and power (CHP) plant that greatly improves the overall operating efficiency. One of the downsides of conventional hot water or steam distribution systems is that the piping systems are expensive to install becaus they must be well insulated to reduce heat loss to the ground. Hot water / steam systems are not able to take advantage low grade waste heat sources such as
It's OK if this GHX is frozen!
In fact, the whole idea of this system is to keep the ground around it frozen. An air craft hangar in Anadyr, Russia, was built on permanently frozen ground. Typically, an expensive, insulated foundation would be built to prevent heat from the building to move into the ground it is built on from melting the permafrost. For this project, pipe was simply laid on the permafrost, covered with about 1' (300 mm) of sand and gravel and 6" (150 mm) of high-density extruded foam insulation. A conventional concrete slab was poured on top of the insulation with radiant floor heat pipe.
A GCHP system was patented in Switzerland in 1912, over a century ago. I was fortunate enough about 9 or 10 years ago to meet one of the pioneers of the industry in Burlington, ON...Mr. Bill Loosley. He installed a GCHP system in his home in 1950. The system used an existing oil furnace as an air handler to move heated air to the home and even had a desuperheater to produce domestic hot water.
For the first three years a diesel motor powered the belt-driven compressor. This was replaced with an electric motor, that still powered the compressor when I visited Mr. Loosley in about 2003 or 2004. The GHX is a direct expansion system where the compressor pumps refrigerant liquid directly through copper pipes buried in the yard behind the home. The system is not designed for cooling, but does provide a percentage of the domestic hot water with a desuperheater connected to the hot water storage tank.
In my blog I'll be expressing my opinions about what I've the learned about ground coupled heat pump (GCHP) systems over the last 30 years. I've been very fortunate to work with many interesting people who are passionate about this technology...engineers, geologists, mechanical contractors, drillers, excavation contractors...in different parts of the world. I've learned a lot from them and will be using this forum to pass on some of the things I've learned and feel are important. Please feel free to use this information if you feel it's worthwhile...hopefully you can avoid some of the same mistakes I've learned from.
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