ground source heating and cooling
Post on 14-Apr-2018
220 Views
Preview:
TRANSCRIPT
-
7/30/2019 Ground Source Heating and Cooling
1/25
Geothermal++++++
Earth Energy
-
7/30/2019 Ground Source Heating and Cooling
2/25
Geo means Earth
Thermal means Heat
Geothermal energy is the natural heat of the Earth
Earth energy is sub-surface heat from the Sun
-
7/30/2019 Ground Source Heating and Cooling
3/25
Capturing Geothermal EnergyThe 1st System
In 1904 1st demonstration. Emerging steam powered a turbine to light
5 light bulbs
Worlds 1st Geothermal Power Station. 1911 in Tuscany, Italy
By 1913 a 250 kW power station had been built and was used to power the
Italian electric railway system. Today world production is 5 TWh, or 10%
-
7/30/2019 Ground Source Heating and Cooling
4/25
Earth Energy Heat PumpA heat pump is an electrical device
that extracts heat from one placeand transfers it to another
-
7/30/2019 Ground Source Heating and Cooling
5/25
-
7/30/2019 Ground Source Heating and Cooling
6/25
-
7/30/2019 Ground Source Heating and Cooling
7/25
Capturing Earth Energy I
Geothermal Heat Pumps can provide heat in thewinter and cool air in the summer best of both
worlds
Residential and commercial/institutional scale is
available.
Geothermal heat pumps can be used anywhere inthe world without a geothermal reservoir. The
insulating properties of the earth, just below our
feet, can keep us warm or cool !!
-
7/30/2019 Ground Source Heating and Cooling
8/25
Energy Under Our Feet
47% of Solar Energy is Absorbed
By the Ground
19% Absorbed by
Water Vapor & Dust
4% Absorbed
By Clouds
17% Reflected
By Clouds6% Absorbed
By Surface
-
7/30/2019 Ground Source Heating and Cooling
9/25
Terms to Know Refrigerant. Liquid/gaseous substance that circulates through the heat pump,
alternately adsorbing, transferring and releasing heat. Commonly usedrefrigerants are distinguished by the fact that over a relatively moderate range
of elevated pressures, they vaporize and condense at temperatures that can
generate spontaneous heat flow to maintain interior building comfort
Classified as hydro-chloro-fluoro-carbons (HCFC), or chloro-fluoro-carbons (CFC).
Todays refrigerants are designed to have minimal impact on the atmosphere by eliminating
the chlorine (hydro-fluoro-carbons)
COP. Coefficient of Performance is a measure of a heat pumps efficiency. It is
determined by dividing the energy output or the heat pump in BTU/hr by the
electrical energy needed in watts to run the pump, at a specific temperature.
The higher the COP, the more efficient the pump.
EER. Energy Efficiency Ratio measures the steady state cooling efficiency of a
heat pump. It is determined by dividing the cooling capacity of the pump in
BTU/hr by the electrical energy input in watts at a specific temperature
-
7/30/2019 Ground Source Heating and Cooling
10/25
More Terms
to KnowCompressor. It squeezes themolecules of the refrigerant, gastogether, increasing the temperature
of the refrigerant shifting it to avapor phase
Evaporator. A coil in which the
refrigerant absorbs heat from the
soil/water and boils to become a low
temperature vapor.Condenser. A coil in which the
refrigerant gives off heat to its
surroundings as it condenses back
into a liquid.
Expansion Device. Lowers the pressurecreated by the compressor. This
causes the temperature to drop, and
the refrigerant becomes a low
temperature vapor/liquid mixture.Evaporator Condenser
Expansion
EvaporationCondensation
Compression
Expansion
Device
Compressor
-
7/30/2019 Ground Source Heating and Cooling
11/25
Ground Source Heat Pumps Source. A ground source heat uses the earth or ground water or
both as the sources of heat in the winter, and as a sink for heatremoved from your home in summer.
Access. The heat is extracted from the earth (land or water) using a
liquid, antifreeze solution, or refrigerant (direct expansion system)
The temperature of the antifreeze is raised by the heat pump
The heat is transferred to the indoor air
Summer reversal heat is taken from indoor air and transferred to the
ground
Delivery.
Forced air
Hydronic radiant
Electrical resistance base board
-
7/30/2019 Ground Source Heating and Cooling
12/25
Ground Source Operation I Location Entire pump system is inside, unlike air source in which
one of the heat exchangers, usually the compressor is outside
Open System
Open System takes advantage of the heat retained in underground body of
water, usually a well.
Water is drawn up directly to the heat exchanger where heat is extracted
Discharge is to a stream, lake or pond, where permitted, or a discharge
well.
Closed System
Collects the heat through an underground system of piping.
An antifreeze solution, or refrigerant, which has been chilled by the heat
pumps refrigeration system to several degrees colder than the soil/water
circulates through the piping and absorbs heat from the soil
-
7/30/2019 Ground Source Heating and Cooling
13/25
Ground Source Operation II Heat Cycle
The antifreeze solution or refrigerant (heat carrier) which has circulated
through the piping and absorbed heat is brought back to the heat pump
in the building.
In the ground water or antifreeze system the carrier passes through the refrigerant
filled primary heat exchanger and transfers the heat In the direct expansion (DX) system the refrigerant enters the compressor directly with
no intermediate heat exchanger
The heat is transferred to the refrigerant, which boils to become a low
temperature vapor - it then goes to the compressor In the open system the ground water is pumped back to the discharge well
In the closed system the heat carrier is pumped through the outdoor piping to be
reheated again
-
7/30/2019 Ground Source Heating and Cooling
14/25
Ground Source Operation III A reversing valve directs the refrigerant vapor to the compressor at
which point the vapor is compressed by reducing the volume and
increasing its temperature.
The reversing value then directs the hotter vapor (gas) to the
condenser coils.
Here it gives up heat to:
Air blowing across the coil and through the duct system to heat the home
Water flowing across the coils and to the radiators in the rooms
Having given up the heat, the refrigerant passes through the
expansion device where the temperature and pressure are decreased
further before returning the the first heat exchanger, or to the DX
system, to begin the cycle again
-
7/30/2019 Ground Source Heating and Cooling
15/25
Technology & OperationHow the Heat Pump Works
Heat pumps transfer heat bycirculating refrigerant through acycle of alternating evaporation
and condensation.
A compressor pumps therefrigerant between 2 heatexchanger coils.
In one coil, the refrigerant isevaporated at low pressure andabsorbs heat from its surroundings(blue in the soil/water).
The refrigerant is then compressedin route to the other coil where itcondenses at high pressure (red)
At this point, it releases the heat itabsorbed earlier in the cycle (intothe home)
Earth Home
Compression
Condensation
Expansion
Evaporation
Evaporator Condenser
Low PressureLow Temperature Liquid
High PressureHigh Temperature Liquid
Low Pressure
Low TemperatureLiquid
Low PressureLow Temperature
Liquid
-
7/30/2019 Ground Source Heating and Cooling
16/25
Heat Pump Ground Loops I
Points to Consider
Size of the system
Ground loop design
Soil Type, Depth and
Consistency
Land area available
-
7/30/2019 Ground Source Heating and Cooling
17/25
Heat Pump Ground Loops II
Vertical
Most appropriate for suburban homeswhere lot space may be restricted.
Pipe inserted into bore holes 6 inches
by 60-200 feet, depending on soil type
and system size
100 m piping per ton of heat capacity(3.5kW or 12,000 BTU)
DX systems smaller holes, less cost
Horizontal
Rural areas with more property
Piping in trenches 3 to 6 m deep
150 m piping per ton of heat capacity
Well insulated 2,000 sq.ft. home
would use 360 to 540 m pipe
-
7/30/2019 Ground Source Heating and Cooling
18/25
Heat Pump Ground Loops III Regardless of the arrangement
chosen, all piping for refrigerantor antifreeze solution systems
must be polyethylene or
polybutylene with thermally fused
joints to ensure leak free
connections for life of the pipe, or
25 to 75 years.
DX systems use copper pipe that is
of refrigeration grade.
Or
PolyethyleneCopper
-
7/30/2019 Ground Source Heating and Cooling
19/25
Heat Pump Ground Loops
Multi-Unit Dwellings
Same principles apply for commercial/institutional settings
In room systems compartmentalized and operate independently
Integration with Solar PV can help optimize benefits
-
7/30/2019 Ground Source Heating and Cooling
20/25
Pipe Installation
New Construction Sites
More Rural
Retro-fit Construction Sites
More Urban
-
7/30/2019 Ground Source Heating and Cooling
21/25
Earth Energy - Advantages
Uses 25% - 50% less energy than conventional heating andcooling
Improved humidity control
Can be retrofitted
Long lasting, quiet and easily accessible Less expensive to operate and maintain
Investment return of 3 to 10 years.or less
It can work in land or waterlots of flexibility
They conserve fossil fuel reserves and enable their use forhigher value products
They provide clean heating and cooling with no emissionsfrom burning fuels
-
7/30/2019 Ground Source Heating and Cooling
22/25
Earth Energy - Disadvantages
High initial cost, particularly for retrofitting
Horizontal ground loop systems which are the least
expensive require a hectare This can be addressed by combining vertical and slinky
systems to reduce spatial requirements
A qualified installer is recommended. However, this
does open the door to financial grants that do not
come with a do it yourself operation
-
7/30/2019 Ground Source Heating and Cooling
23/25
Benefits of Heat Pumps
They can be used almost everywhere world wide
They are energy and cost efficient
They conserve fossil fuel reserves and enable their
use for higher value products
They provide clean heating and cooling with noemissions from burning fuels (depending on
electricity source)
-
7/30/2019 Ground Source Heating and Cooling
24/25
Geothermal Benefits
Replacing your natural gas
furnace is equivalent to
parking 2 cars for a year.
EPA: Geothermal heat pump
systems are the most energy
efficient, environmentally
clean, and cost effective
space conditioning systemsavailable
Originates from
the electricity
source
-
7/30/2019 Ground Source Heating and Cooling
25/25
Summer/Winter Operation
Winter Heating Cycle Winter Cooling Cycle
top related