Performance of Rotary Enthalpy Exchangers
Date
1994Author
Stiesch, Gunnar
Publisher
University of Wisconsin-Madison
Metadata
Show full item recordAbstract
Rotary regenerative heat and mass exchangers allow energy savings in the heating and cooling of
ventilated buildings by recovering energy from the exhaust air and transferring it to the supply air
stream. In this study the adsorption isotherms and the specific heat capacity of a desiccant used
in a commercially available enthalpy exchanger are investigated experimentally, and the
measured property data are used to simulate the regenerator performance and to analyze the
device in terms of both energy recovery and economic profitability.
Based on numerical solutions for the mechanism of combined heat and mass transfer
obtained with the computer program MOSHMX for various operating conditions, a
computationally simple model is developed that estimates the performance of the particular
enthalpy exchanger and also of a comparable sensible heat exchanger as a function of the air
inlet conditions and the matrix rotation speed. The model is built into the transient simulation
program TRNSYS, and annual regenerator performance simulations are executed. The
integrated energy savings over this period are determined for the case of a ventilation system for
a 200 people office building (approx. 2 m3/s) for three different locations in the United States,
each representing a different climate.
Life cycle savings that take into account the initial cost of the space-conditioning system
as well as the operating savings achieved by the regenerator are evaluated for both the enthalpy
exchanger and the sensible heat exchanger over a system life time of 15 years. The present
worth of the accumulated savings ranges from $ 28,000 to $ 38,000 for the enthalpy
exchanger and from $ 7,000 to $ 24,000 for the sensible heat exchanger. The enthalpy
exchanger results in greater payoffs in all locations, but its advantage is most significant in a
warm and humid climate where the sensible heat exchanger performs poorly.
Subject
Dissertations Academic Mechanical Engineering.
Thesis (M.S.)--University of Wisconsin--Madison, 1994.
University of Wisconsin--Madison. College of Engineering.
Permanent Link
http://digital.library.wisc.edu/1793/7881Description
Under the supervision of Professor Sanford Klein; 153pp.
Citation
Stiesch, G. (1994). Performance of Rotary Enthalpy Exchangers. Master's Thesis, University of Wisconsin-Madison.