IR Enchange Between a Solar Collector with Plastic Glazing and the Sky
File(s)
Date
2000Author
Lekube, Juan
Publisher
University of Wisconsin-Madison
Metadata
Show full item recordAbstract
Two types of the absorption chillers, the single and half effect cycles, can operate using low
temperature hot water. The advantage of the single effect over the half effect cycle is the
higher COP but the single effect has a narrower temperature operating range. The half effect
has the capability of using lower hot water temperature but the lower COP increases
operating cost and requires investing a larger cooling tower. A detailed computer model was
written for the single and half effect cycles based on heat transfer coefficients for the inside
and outside tubes of each component [generator, absorber, condenser, and evaporator],
energy, mass, salt balances, and rate equations. The single effect component model was
calibrated with known data from a US absorption chiller manufacturer. The cooling tower
was modeled using the analogy approach, calibrated and validated with performance data
from a cooling tower manufacturer. Capacity and dollars per ton were used to determine
lower limits on the firing temperature. The results show that at 225oF (107 C) at 2000 gpm
(7570 L/min) of hot water, the cost to maintain capacity starts to change for the single effect
cycle. At 205oF (99 C) the cost to maintain capacity increases rapidly. The half effect cycle
can maintain capacity at temperatures as low as 185oF (82 C) hot water at 2000 gpm (7570
L/min) without a large increase in capital investment. The capital cost for the half effect
chiller system is 200 $/ton (57 $/kW) more than the single effect, using hot water
temperatures above 200 oF (93 C). The single effect cycle can only be competitive with an
electric centrifugal chiller if the heat source is free or a combination of high electrical cost
with a low cost of heat. The half effect cycle can be competitive with the single effect if the waste heat is free and the
temperature is below 200oF (93 C) or has a low flow rate in the range of 1000 gpm (3785
L/min).
Subject
Thesis (ITSI)--University of Wisconsin--Madison, 2000.
Dissertations Academic Mechanical Engineering.
University of Wisconsin--Madison. College of Engineering.
Permanent Link
http://digital.library.wisc.edu/1793/7648Description
Under the supervision of Professors Sanford Klein and William Beckman; 120pp.
Citation
Lekube, J. (2000). IR Enchange Between a Solar Collector with Plastic Glazing and the Sky. Master's Thesis, University of Wisconsin-Madison.