Direct GeoExchange is today's most effective
method of harvesting the earth's renewable
energy for the purpose of providing domestic hot
water and heating/cooling for buildings. Highly
versatile, EarthLinked's refrigerant flow controls have
successfully operated commercial refrigeration
systems, air source heat pumps from one to
15-ton capacity, a variety of GeoExchange
systems produced by five manufacturers,
closed-loop units of three manufacturers,
multi-compressor units, and radiant hydronic
heating systems. These unique flow controls also
make possible the inclusion of desuperheating or
integrated water heating on any heat pump system
without the need for electronic controls.
Until the development of EarthLinked's Refrigerant
Flow Controls, no simple controls or metering
devices existed that could deliver refrigerant
in the condition appropriate to each component
throughout the entire operating cycle and
continually maintain stable refrigerant
conditions.
Special refrigerant flow controls were
necessary to manage the refrigerant in the long
evaporator-condenser which is buried in direct
contact with the heat source. EarthLinked's refrigerant
management system serves this need and provides
multiple additional advantages.
Refrigerant Management Objectives
- Stable refrigerant management in long
evaporator/condenser under all loading
conditions.
- Continuously return lubricating oil to the
compressor without any liquid refrigerant.
- Improved system efficiency, reliability and
serviceability.
Geothermal Heating Explained.
Geothermal Cooling Explained.
To operate at optimum efficiency, the three
major components of all heat pumps require the
refrigerant to be in a particular physical state
appropriate to each component (the compressor,
condenser and evaporator). The compressor needs
a dry refrigerant vapour from the evaporator,
containing little or no superheat at the
compressor inlet. The condenser needs its
refrigerant outlet pressure to be just
sufficient to cause the refrigerant vapour to
complete its condensing just before it reaches
the condenser outlet. This provides high
pressure vapour to the entire condenser for
maximum condensing with no uncondensed vapour
passing through the condenser and no liquid
refrigerant "backed up" in the condenser (which
produces subcooling).
In contrast, the
evaporator needs liquid refrigerant at its
inlet. The liquid should then complete its
evaporation just as it reaches the evaporator
outlet. This is the optimum "flooded" evaporator
condition which produces maximum system
efficiency when no portion of the evaporator is
wasted in producing superheat. Any unevaporated
refrigerant which passes through or out of the
evaporator should not reach the compressor.
Conventional controls include thermostatic
expansion valves (TXVs), electronic expansion
valves (EXVs), automatic expansion valves
(AXVs), fixed orifices, capillary tubes, and
accumulators. No combination of these can assure
simple, stable operation of a Direct GeoExchange
system or achieve all the following conditions
which EarthLinked's controls maintain in any standard
air conditioning system, including:
- A fully condensing condenser (minimal
subcooling).
- A continuously flooded evaporator (no
superheat).
- Dry vapour with no superheat at the
compressor inlet.
- A simple, easy method of determining when
the system is properly charged.
Other Applications
The inherent simplicity and adaptability of
EarthLinked controls has been proven since 1984. These
controls have increased the efficiency of a
variety of systems produced by 16 different
manufacturers, including air source heat pumps
(15% efficiency gain), air conditioners; closed
loop GeoExchangers (loop length can be reduced
by approximately one-fourth because of system
efficiency introduced by the ACC and LFC);
hundreds of other Direct GeoExchange systems
(including inoperable and inefficient units
previously produced by others); Direct
GeoExchange water heaters; and radiant hydronic
systems which also produce domestic hot
water.
