下面是需要翻译的内容： 拜托高手帮忙！！！！！！！！ 相信对高手是小菜一碟，对我就是救命啊！！！！！拜托帮忙
Run-around Coil Systems
Install run-around coils in applications with large
dehumidification requirements where the air must be reheated
after passing the cooling coil.
A run-around coil system is a simple piping loop with an
upstream precooling coil and a downstream reheating coil that
sandwiches the main cooling coil. The circulating fluid is
pumped to transfer heat from the warm mixed air to the off coil
cold supply air. The run-around system reduces the cooling
load on the main cooling coil; reheat is provided by the heat
picked up by the circulating fluid in precooling coil instead of by
an external source of expensive energy.
In new building designs and retrofits, a run-around system can
reduce peak heating and cooling loads as well as total heating
and cooling energy. The run-around system can have a
significant impact on the heating and cooling capacity in new
HVAC designs.
The heat recovery effectiveness of the run-around loop is
defined as the ratio of the actual heat transfer to the maximum
possible heat transfer between the air streams. This is
equivalent to the ratio of the difference between the mixed air
temperature and the air temperature off the precool coil to the
difference between the mixed air temperature and the air
temperature off the main cooling coil. The effectiveness ranges
from 50% for a normal loop to 65% for a high performance
loop. Because of the relatively small temperature differences
between the energy exchange coils, low approach cooling coils
should be used. Designers must account for the additional
pressure drop from the added coil.
Run-around coil systems are most applicable in situations
requiring substantial dehumidification.
Recommendation
Descri ption
Figure 7-4. Runaround
loop
cooling system.
Applicability
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只看楼主 我来说两句-
marsboymxx
沙发
来个人帮帮忙啊！！！！！！！！！！！！！！！！！！！！！！！！！1
2006-05-31 22:10:31
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marsboymxx
板凳
􀂃 Simple system with no moving parts or external connections
2006-05-31 22:07:31
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makes it basically maintenance free.
The increased dehumidification capacity provided by heat pipes
allows for a smaller cooling system. However, the addition of
heat pipes will increase the pressure drop, and fan power must
be adjusted accordingly.
Heat pipes can either be applied to existing HVAC systems or
can be installed at the factory. The heat pipe loop is usually
controlled by cycling on-off or modulating the refrigerant flow
with a control valve.
Heat Pipe Technologies product selection software,
www.heatpipe.com.
The installation cost of a heat pipe loop for a cooling system is
approximately $2.50/cfm.
The cost effectiveness of heat pipes depends on the system it
is replacing. When used instead of a dehumidifying system
requiring reheat, the simple payback is two to three years.
However, when the system replaces a system without reheat
(that is, no humidity control), there are additional benefits
including increased comfort and enhanced indoor air quality,
which are difficult to quantify.
Some heat pipe applications require the same routine
maintenance as any air conditioning unit. Valveless units
require no maintenance aside from cleaning. Valved units have
normal balancing requirements.
The precooling and reheating heat pipes should be installed
closely to sandwich the main cooling coil.
A Dinh-style heat pipe dehumidification system was installed in
the air handling system (19,000 cfm) in Building 49 at the
EPA’s Gulf Breeze laboratory in Pensacola, Florida, in 1996. The
heat pipe was effective in reducing inside humidity levels by
about 10%, from an average of 75% before installation to an
average of 65% after installation, without affecting the inside
Benefits
Integrated
Design
Implications
Design Details
Design and
Analysis Tools
Costs
Cost
Effectiveness
Operations and
Maintenance
Commissioning
Case Study
© 2003 Eley Associates on behalf of State of Hawaii DBEDT 7-19
HAWAII COMMERCIAL BUILDING GUIDELINES FOR ENERGY EFFICIENCY
DEHUMIDIFICATION
temperatures. An additional 20 tons of mechanical cooling
would have been necessary to provide this additional
dehumidification during peak conditions.
The heat pipe cost $42,000 to install; the additional mechanical
cooling equipment necessary to provide the same level of
dehumidification would have cost $30,000. Therefore the
additional cost of installing a heat pipe instead of mechanical
cooling to provide the 10% lower indoor humidity was $12,000.
Using a weather bin method analysis, the heat pipe in this
location provides a maximum 20 tons of precooling and 240
kBTU/h of reheat with no energy input, saving an estimated 56
kW in peak summer demand, 153,775 kWh in annual energy
consumption (about 10% of the total), and $7,700 in annual
energy costs. The simple payback of using a heat pipe to
provide the enhanced dehumidification for this installation is
therefore 15 months. The payback will vary for other
installations based on weather data, mechanical system
efficiencies, and utility rates.
A comparison of the EPA Building 49 utility bills for the 12
months before installation and the 12 months following
installation, normalized for weather variations, showed an
actual energy reduction of 230,750 kWh (14%) and a cost
reduction of $9,980.
Heat Pipe Technologies, www.heatpipe.com
Island Energy Systems (sales representative)
Contact: Joseph Petrie
PO Box 316, 111
Kaapahu Road, Paauilo, HI 96776
Phone: 808-776-1333
Fax: 808-776-164
Heat Pipe Technologies, www.heatpipe.com
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