A Ceiling Radiant Cooling
System with well water
Author:
Hideo Asada, Guest Researcher
NWO (Netherlands Organisation for Scientific Research)
Delft University of Technology, The Netherlands,
Faculty of Architecture
Introduction
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A two-storey wooden house in Chiba, Japan.
Equipped with a ceiling radiant cooling system
Energy source: well water.
Outdoor sun shading on the South-facing window.
Measurements of indoor thermal environment and
electric power consumption in were conducted
(summer 2001)
System description (1)
• The ceiling radiant cooling system was installed in
the living room
• The living room window faces south
South view
Living room (West)
System description (2)
• Water from the deep well is pumped up and mixed
with return water from the ceiling radiant panel by
the three way valve to maintain the temperature at
a the set point.
• The circulation pump enables this mixed water to
run within the panel and cool it. A portion of the
return water is sent to the three-way valve and the
rest is discarded via the percolation well.
Measurements
• Indoor thermal environment and energy use was measured
during the summer season in Japan
• Ca. 80 points were measured and a digital data recorder
was used to log data at one-minute intervals.
• Measurements were carried out with and without outdoor
sun shading on the South-facing window
• When applied, sun shading was used during ceiling radiant
cooling system operation hours, from 10:00 to 16:00. The
radiant panel surface temperature was set at 22ºC.
Indoor thermal environment in summer
• room air temperature was almost constant at 28 ° C.
• globe temperature was about 1 °C below room air.
Exergy flows (with sun shading)
■ The ceiling panel:
• consumed 7 W of cool thermal exergy.
• emitted 10 W of cool exergy by radiation and
10 W by convection.
• received 2 W of cool radiant exergy from
surrounding walls.
■ The well water pump:
• consumed about 400 W of exergy. It is 30 to
56 times more exergy than the ceiling radiant
panel.
Exergy flows on the floor
Conclusions (2)
■ The floor surface:
• consumed most exergy as solar exergy from the
window.
• also consumed cool radiation exergy from ceiling
and surrounding walls, to remove solar heat from
the floor surface.
• It is important to reduce solar exergy incident on
the floor.
Summary
• The path of exergy input and consumption was
shown.
• Cool radiation exergy from ceiling and walls were
consumed to remove solar heat from the floor
surface.
• Electric power for pumping accounted for the
largest exergy consumption in the system.