Editing Heat recovery ventilation (section)

=== Fixed plate heat exchanger ===
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[[File:Heat exchanger.svg|thumb|280x280px|Types of [[heat exchanger]]s.{{citation needed|date=April 2022|reason=Source needed for efficiencies.}}|alt=]]

Fixed plate heat exchangers have no moving parts, and consist of alternating layers of plates that are separated and sealed. Typical flow is cross current and since the majority of plates are solid and non permeable, sensible only transfer is the result.

The tempering of incoming fresh air is done by a heat or energy recovery core. In this case, the core is made of aluminum or plastic plates. Humidity levels are adjusted through the transferring of water vapor. This is done with a rotating wheel either containing a desiccant material or permeable plates.<ref>Huelman, Pat, Wanda Olson. [http://www.extension.umn.edu/distribution/housingandclothing/dk7284.html Common Questions about Heating and Energy Recovery Ventilators] {{webarchive|url=https://web.archive.org/web/20101230120234/http://www.extension.umn.edu/distribution/housingandclothing/DK7284.html |date=2010-12-30 }} University of Minnesota Extension. 1999. 2010.</ref>

Enthalpy plates were introduced in 2006 by Paul, a special company for ventilation systems for [[passive house]]s. A crosscurrent countercurrent air-to-air heat exchanger built with a humidity permeable material. Polymer fixed-plate countercurrent energy recovery ventilators were introduced in 1998 by Building Performance Equipment (BPE), a residential, commercial, and industrial air-to-air energy recovery manufacturer. These heat exchangers can be both introduced as a retrofit for increased energy savings and fresh air as well as an alternative to new construction. In new construction situations, energy recovery will effectively reduce the required heating/cooling capacity of the system. The percentage of the total energy saved will depend on the efficiency of the device (up to 90% sensible) and the latitude of the building.

Due to the need to use multiple sections, fixed plate energy exchangers are often associated with high pressure drop and larger footprints. Due to their inability to offer a high amount of latent energy transfer these systems also have a high chance of frosting in colder climates.

The technology patented by Finnish company RecyclingEnergy Int. Corp.<ref>[http://www.recyclingenergy.com Recycling Energy]</ref> is based on a regenerative plate heat exchanger taking advantage of humidity of air by cyclical condensation and evaporation, e.g. latent heat, enabling not only high annual thermal efficiency but also microbe-free plates due to self-cleaning/washing method. Therefore, the unit is called an enthalpy recovery ventilator rather than heat or energy recovery ventilator. Company's patented LatentHeatPump is based on its enthalpy recovery ventilator having COP of 33 in the summer and 15 in the winter.

Fixed plate [[heat exchangers]] are the most commonly used type of heat exchanger and have been developed for 40 years. Thin metal plates are stacked with a small spacing between plates. Two different air streams pass through these spaces, adjacent to each other. Heat transfer occurs as the temperature transfers through the plate from one air stream to the other. The efficiency of these devices has reached 90% sensible heat efficiency in transferring sensible heat from one air stream to another.<ref>{{Cite journal|last1=Nielsen|first1=Toke Rammer|last2=Rose|first2=Jørgen|last3=Kragh|first3=Jesper|date=February 2009|title=Dynamic model of counter flow air to air heat exchanger for comfort ventilation with condensation and frost formation|journal=Applied Thermal Engineering|volume=29|issue=2–3|pages=462–468|doi=10.1016/j.applthermaleng.2008.03.006|bibcode=2009AppTE..29..462N |issn=1359-4311}}</ref> The high levels of efficiency are attributed to the high heat transfer coefficients of the materials used, operational pressure and temperature range.<ref name=":1"/>