Boreal ACDX-45, Руководство по установке

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2005 Boreal Geothermal Inc. www.boreal-geothermal.com
Introduction to “ ACDX ” Technology
Direct earth coupled heat pump or “ACDX” heat pump is
one that has its refrigerant evaporator / condenser in direct ther-
mal contact with the earth from which heat is either extracted
from during the heating mode or introduced to during the cool-
ing mode of operation.
The general refrigeration cycle of our ACDX machine is
similar in nature to a conventional water-to-air or water-to-
water heat pump in that there exist a compressor, expansion
device, reversing valve, and refrigerant-to-air heat exchanger.
Conventional technology concerned with heat pumps relies
upon the transfer of heat from the ground by means of a secon-
dary heat exchanger system and working fluid, e.g., water,
which is pumped to the geothermal unit located in the heated
structure. The conventional heat pump has it’s own internal
primary heat exchanger which extracts heat (heating mode) or
rejects heat (cooling mode) from this water, which is then
pumped back to the earth to be reheated or cooled.
ACDX systems similarly use a ground coil system, how-
ever, the working fluid is a refrigerant and the copper ground
loop is the primary heat exchanger. Such geothermal heat ex-
change is an efficient and effective way of achieving heat ex-
change in heating and air conditioning systems, and especially
heat pump type systems. Since the ground temperature is rela-
tively constant at 48
o
F at a depth 6 ft. below the frost line, the
available heat is constant.
The elimination of the secondary earth heat exchanger
(typically plastic in nature) and its associated working fluid
reduces the temperature difference required between the ground
and the evaporating refrigerant yielding a higher suction pres-
sure than a conventional system under similar circumstances
and thus a higher efficiency.
Many attempts have been made in the past to develop suc-
cessful direct coupled heat pumps for residential and commer-
cial uses. These attempts have failed adequately to meet a num-
ber of requirements associated with an economically and func-
tionally viable system. Some of the shortcomings included:
I. Inadequate oil return to the compressor primarily in the
heating mode.
II. Inadequate evaporator length and spacing for properly ex-
tracting heat from the earth resulting in low capacity and
low efficiency of the systems.
III. Refrigerant charges in the range of 10 times greater than a
similar capacity conventional geothermal heat pump.
IV. Approximately 3 times as much refrigerant required in the
cooling mode as is required in the heating mode.
V. Lack of a proper means to store additional refrigerant re-
quired during the cooling operation but not needed during
the heating mode.
VI. Inefficient and ineffective method to account for vastly
varying condenser capability depending on ground tem-
perature.
VII. Difficulty in providing an easy to install system of earth
exchanger loops.
The BOREAL® solution has been to start with a clean
new concept and to design a unit from the ground up. We
started by developing an evaporator system that would yield
the best performance to pressure drop factor and which
would impact enough area to maintain a minimum suction
pressure above 40 Psig. The current horizontal ground loop
comprises 350 ft. per ton of 1/2” OD copper tubing. A 3 ton
system would have 3 such loops working in parallel during
the heating mode. Refrigerant charge had been determined
to be 5 lbs. of R-22 per loop. These 1/2” copper loops main-
tain sufficient velocity at all times to insure adequate oil
return. During cooling mode the machine automatically se-
lects one or more loops based on discharge pressure to act as
the condenser. As the discharge pressure builds to a prede-
termined point, the on-board computer selects the most ap-
propriate combination of ground loops to dissipate the heat
at the lowest cost to the homeowner. By intelligently con-
trolling the manner in which the condenser is utilized our
total system charge does not have to be altered nor does an
excess charge have to be stored anywhere.