INTRODUCTION from a heat source to a heat

INTRODUCTION

In present scenario everybody in world concernedabout global
warming, ozone layerdepletion, greenhouse gases, deforestation and many more
things happens after the industrialization and revolution.Many new ways were came
in existence for reducing the pollution.Renewable energy attracts attention of
people and scientists.Geothermal energy is one of best gift of earth. This
energy can be used without any disturbance to environment.

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The adjective geothermal originates
from the Greek roots ??(ge), meaning earth, and ??????(thermos),
meaning hot.Heat is a form of energy and geothermal energy is,
literally, the heat contained within the Earth that generates geological
phenomena on a planetary scale (Dickson and fanelli,2004).(Geothermal energy is not only available in the form
of volcanoes, hot water streams, but whole earth surface is a source of energy
throughout the year.)Temperature of earth below 2 – 3 meter
remains in the particular range throughout the year. At 3 m depth it is between 24ºC and 29.8ºC.
The strata between 2-3 m appear well suitedfor sitting of earth tube heat
exchanger (Sharan and Jadhav. 2002).

 

Geothermal heating and cooling involves the use of
constant heat (geothermal energy) that exists two to three metres below ground
for heating and cooling purposes (stein,2013). It can be described
schematically as ‘convecting water in the upper crust of the Earth, which, in a
confined space, transfers heat from a heat source to a heat sink, usually the
free surface’. (Hochstein et
al.,1990)

 

UTILIZATION OF GEOTHERMAL RESOURCES

The Lindal diagramemphasises two
important aspects of the utilization of geothermal resources(a) with cascading
and combined uses it is possible to enhance the feasibility of geothermal
projects and (b) the resource temperature may limit the possibleuses
(Gudmundsson, 1988).

1.      Electricity
generation mainly takes place in conventional steam turbines and binaryplants,
depending on the characteristics of the geothermal resource.

2.      Direct heat use is one of the oldest, most versatile and also
the most common form of utilization of geothermal energy. Bathing, space
heating and district heating, agricultural applications, aquaculture and some
industrial uses are the best known forms of utilization, but heat pumps are the
most widespread. There are many other types of utilization, on a much smaller
scale, some of which are unusual.

3.      Space
cooling is a feasible option where absorption machines can be adapted
togeothermal use. Thetechnology of these machines is well known, and they are
readily available in the market. The absorption cycle is a process that
utilises heat instead ofelectricity as the energy source(Sanner, et al.
2003).

4.      Ground-coupled
and ground-water heat pump systems have now been installed in great numbers in
at least 30 countries, for a total thermal capacity of more than 9500 MWt (in
2003) (Lund et al. 2003).

5.      Agricultural applicationsof geothermal fluids consist
of open-field agriculture and greenhouse heating. Thermal water can be used in
open-field agriculture to irrigateand/or heat the soil (Barbier and Fanelli,
1977).

6.      Farm animalsand aquatic species, as well as vegetables
and plants, can benefit in qualityand quantity from optimum conditioning of
their environmental temperature.In many cases geothermal waters could be used
profitably in a combination of animalhusbandry and geothermal greenhouses (Barbier
and Fanelli, 1977).

GEOTHERMAL HEATING AND COOLING SYSTEM

Geothermal Heating and Cooling Systems provide space conditioning
heating, cooling, and humidity control. They may also provide water heating
either to supplement or replace conventional water heaters. Geothermal Heating
and Cooling Systems work by moving of heat, rather than by converting chemical
energy to heat like in a furnace. Every Geothermal Heating and Cooling Systems
has three major subsystems or parts: a geothermal heat pump to move heat
between the building and the fluid in the earth connection, an earth connection
for transferring heat between its fluid and the earth, and a distribution
subsystem for delivering heating or cooling to the building.

 

 

 

 

Geothermal system components

a.)Ground loop 

A closed ground loop system
consists of a series of high density polyethylene pipes buried in a yard. A
heat transfer fluid, comprised of antifreeze and water, is inside the ground
loop pipes. This heat transfer fluid removes heat from (heating mode) or
delivers heat to (cooling mode) the earth surrounding the ground loop. The
ground loop pipes carry the heated fluid to the heat pump furnace unit in the
home (MH, 2017).

b.)Geothermal
Heat Pump

The heat pump’s system
improves the consistency of the heat, which is then circulated throughout the animal
house by way of the distribution system. The heat pump furnace unit provides
both heating and cooling.The
geothermal heat pump is packaged in a single cabinet, and includes the
compressor, loop-to-refrigerant heat exchanger, and controls(MH,
2017).

c.)Distribution
Subsystem

In a forced air system,
a fan in the heat pump furnace unit blows air over a fan coil and the heated or
cooled air is distributed through the ductwork(MH, 2017).

 

Different
Types of geothermal ventilation Systems

Geothermal
systems use the earth as a heat source and heat sink. A series of pipes,
commonly called a “loop,” carry a fluid used to connect the
geothermal system’s heat pump to the earth.

There are
two basic types of loops: closed and open, where as other variants are also
present.

Open
loop systems

 Open loop
systemsare the simplest. Used successfully for decades, ground water is drawn
from an aquifer through one well, passes through the heat pump’s heat
exchanger, and is discharged to the same aquifer through a second well at a
distance from the first.Open-loop systems have a very high
thermal efficiency and installation can be up to 50% less expensive than
vertical closed loop systems. Open
loop systems have challenges like some local ground water chemical conditions
can lead to fouling the heat pump’s heat exchanger.Increasing environmental
concerns mean that local officials must be consulted to assure compliance with
regulations concerning water use and acceptable water discharge methods(Wale
and Attar,2013).

Closed
loop system

Closed loop systems are becoming the most common. When
properly installed, they are economical, efficient, and reliable. Water (or a
water and antifreeze solution) is circulated through a continuous buried pipe keeping.
The closed loop system is environment friendly because water in the loop
prevents contamination to the external environment. The length of loop piping
varies depending on ground temperature, thermal conductivity of the ground,
soil moisture, and system design(Wale and Attar,2013).

Horizontal
Loops

Horizontal closed loop installations are generally
most cost-effective for small installations, particularly for new construction
where sufficient land area is available. These installations involve burying
pipe in trenches dug with back-hoes or chain trenchers. Up to six pipes,
usually in parallel connections, are buried in each trench, with minimum
separations of a foot between pipes and ten to fifteen feet between trenches(Wale
and Attar,2013).

Vertical
Loops

Vertical closed loops are preferred in many situations
like small farm size or no more land is available for further enhancement. Vertical
loops also minimize the disturbance to existing landscaping. For vertical
closed loop systems, a U-tube(more rarely, two U-tubes) is installed in a well
drilled 100 to 400 feet deep. Because conditions in the ground may vary
greatly, loop lengths can range from 130 to 300 feet per ton of heat exchange.
Multiple drill holes are required for most installations, where the pipes are
generally joined in parallel or series-parallel configurations(Wale and
Attar,2013).

Slinky
loops:

Increasingly, “slinky” coils overlapping coils of
polyethylene pipe are used to increase the heat exchange per foot of trench,
but require more pipe per ton of capacity. Two pipe systems may require 200 to
300 feet of trench per ton of nominal heat exchange capacity. The trench length
decreases as the number of pipes in the trench increases or as Slinky coil overlaps
increases.This
same slinky coil design-system can be used in a lake or pond application(Wale and Attar, 2013).

Pond
loops

Pond closed loops are a special kind of closed loop
system. Where there is a pond or stream that is deep enough and with enough
flow, closed loop coils can be placed on the pond bottom. Fluid is pumped just
as for a conventional closed loop ground system where conditions are suitable,
the economics are very attractive, and no aquatic system impacts have been
shown (Wale and Attar, 2013).

 

 

Anatomy of a
Geothermal Heat Pump (GHP)

Instead of producing
heat like a conventional furnace, a geothermal system moves heat from one place
to another.

Ø 
The cool, liquid refrigerant enters the indoor coil
during cooling. As it enters the coil, the temperature of the refrigerant is
between 40o and 50o F.

Ø 
As warm, moist room air passes over the cool coil,
the refrigerant inside absorbs the heat.

Ø 
The new cooler, drierair is circulated back into
the room with a blower fan.

Ø 
The refrigerant moves into the compressor, which is
a pump that raises the pressure so it will move through the system. The
increased pressure from the compressor causes the refrigerant to heat to
roughly 120º to 140º F.

Ø 
The hot vapor now moves into the condenser (the
underground loops), where the refrigerant gives up its heat to the cooler
ground and condenses back into a liquid.

Ø 
During the winter, the reversing valve switches the
indoor coil to function as the condenser, and the underground piping to act as
the evaporator.

Ø 
As the refrigerant leaves the compressor, it’s
still under high pressure. It reaches the expansion valve, where the pressure
is reduced.

Ø 
The cycle is complete as the cool, liquid
refrigerant re-enters the evaporator to pick up room heat.

Ø 
During the winter, the reversing valve switches the
indoor coil to function as the condenser, and the underground piping to act as
the evaporator.

Ø  In short, the indoor
coil and underground piping cause the refrigerant to change state, absorbing
and releasing heat through boiling and condensing. The compressor and expansion
valve move the refrigerant through the system by changing the pressure(Wale and Attar, 2013).

 

Calculation
of geothermal ventilation and energy requirement:

 

The ventilation required for the
bird/animal is found using this equation:

V?
= no. of birds/animals X average body weight X flow rate per kg                       

 

 

 

Geothermal energy supplies

Tocalculate this amount
of heat that can be supplied to the house we use the following equation:

QGeo=
m.GeoX C?
X (TGeo–Ti)                                                              

Where, QGeo      =Water temperature(oC)

m.Geo    = Ground water mass flow rate (kg/s)

                                    C?       =Air
specific heat (kJ/kg.K)

                                    TGeo        =Ground
water temperature (oC)

(Busoul
and Elayyan, 2014)

 

ADVANTAGES OF GEOTHERMAL SYSTEMS

Efficiency:  energy
efficiency ratio of geothermal ventilation system compare to electrical heating
at different temperature (°C) like 32.2, 37.7, 43.3 is 17 and 10.5, 9, 8,
respectively(Choudhury,
2013).

Reliability and safety: Geothermal heating and cooling
systems have few moving parts, so they are highly reliable.There is no risk of
vandalism.Geothermal heating systems can last far longer than most heating
systems up to 25-50 years. It will also eliminate the risk of carbon monoxide
poisoning associated with natural gas heating and hot water. The risk of fires
is also much lower than in an animal house equipped with a gas furnace and/or
gas water heater.

Flexibility and convenience: Geothermal heat pumps can be set up
to supply hot water as well as space heating and cooling. In some cases, the
hot water comes at no additional energy cost.Geothermal heating and cooling
systems create no noise outside the home, and almost no noise inside either
(Choudhury, 2013).

Renewable energy: Geothermal is a renewable source of
energy for heating, cooling, and air conditioning. There is no pollution caused
and no any adverse effects on flora or fauna.Geothermal heating and cooling
systems do not contribute to global warming (Choudhury, 2013).

Financial: Although geothermal systems can cost several
times what a conventional system costs, payback can be within 2-10 years
according to some estimates. This system is more economical as compared to heating
ventilation and air cooling (HVAC) system (Choudhury, 2013).

 

DISADVANTAGESOF GEOTHERMAL SYSTEMS

1.      Expensive: These systems are very expensive to install.

2.      Installation disturbance:  During the time of installation trenching is
required for loop establishment it will disturb the land structure. In case of
horizontal loop system disruption of landscape is seen.

3.      Environmental disadvantages of
geothermal systems using direct exchange (DX): Use of copper pipes to circulate the refrigerant, and
copper pipes buried under ground can easily corrode over time, leading to leaks
that are hard to locate and almost impossible to fix (GEEH, 2016).

                            

ENVIRONMENTAL EFFECTS

The environmental effects of geothermal development
and power changes in land use associated with exploration andplant
construction, noise and sight pollution, thedischarge of water and gases, the
production of foulodor, and soil subsidence. Most of those effects,however, can
be mitigated with current technology sothat geothermal uses have no more than a
minimalimpact on the environment. For example, KlamathFalls, Oregon, has
approximately 600 geothermal wellsfor residential space heating

In addition, GHPs have a very minimal effect on the
environment, because they make use ofshallow geothermal resources within 100 meters
(about 330 feet) of the surface. GHPscause only small temperature changes to
the groundwater or rocks and soil in the ground (EB, 2017).

Geothermal HVAC Myths Busted

There
are many myths about the geothermal ventilation system like geothermal energy
is just experimental and can’t be used widely. Geothermal resources are
nonrenewable. Extraction and injection of geothermal brines will contaminates
the drinking water. Geothermal ventilation development will disturbs the land features.
Geothermal ventilation is applicable only in temperate region of earth.
Geothermal ventilation system can’t cool the home it will only heat the room(Egg,2013).

Morrison
and Ahmed, (2010) reported myth about GHPS that the technology is too
expensive. The technology doesn’t work in India. Geothermal HVAC requires
geothermal energy to operate.

 

 

Geothermal system in different animal house

Shah,
et al.,(2017) found that earth-to-water heat exchanger(EWHE) pens were
slightly warmer than the Control pens cooled with stir fans and sprinklers in
very hot days, pig performance in the EWHE pens was unaffected. The EWHE
reduced the electricity use by >50 per cent and eliminated the sprinkling
water use. EWHE is sustainable and cost effective for high value pig and
greenhouse in any part of the world.

Kankariya
Zoo, Ahmedabad has initiated a project to develop a nocturnal animal house with
the geothermal ventilation system for providing a fresh air at ideal temperature
which is good for the under danger wild animal species (IE, 2017).

Geothermal
cooling system potentially reduces the cost of energy about 28 per cent as
compared to conventional heating system. Geothermal ventilation suppresses the
emissions of (NH3, H2S, SO2) and also the risk
of microbial contaminant into the animal house environment. It has no any
negative impact on the growth performance of the growing pigs.(Bostami et
al. 2016). They further suggested that, geothermal system was more
effective in maintenance ofinternal house temperature compared to ground
channel; whereas, ground channel system was more effective in savingenergy
consumption and reducing CO2 emissions. Thus, on a broader view,
geothermal andground channel system can contribute to the global energycrisis
and global gas emissions reduction through potentialsaving of energy consumption
and reduction of CO2 and odorous gas emissions (Bostami et al.
2016).  

Islam,
(2016) found that the CSGHP system has the potential to reduce electricity use,
overall cost and CO and noxious gas emissions. Therefore, the CSGHP system has
the potential for use as an environmentally friendly renewable energy source
for animal houses.

Copenhagen
Zoo had conducted a project for preliminary study of geothermal ventilation
system for their zoo animals and birds. They have done project for penguin
exhibition and they have save about 142 MWh energy per year (Hestmark et
al., 2015).

            Use of a modular housing with GHE may be more effective for heat-intensive
piglet production. The investment costs are higher than in comparable
conventional livestock buildings. The modular housing with integrated GHE is
assessed as positive from energy and environmental point of view for pig houses
where high indoor temperatures are required on a year-round basis(Krommweh et
al., 2014).

Predicala
et al., (2014) conducted an experiment on swine barn and found that
geothermal ventilation system is more significant than the convention gas fired
heater, GSHP room was cooler during the warm months there were no considerable
difference between two rooms during cold months. Methane and Nitrous Oxide
concentrations were lower in GSHP room compare to conventional ventilation
system. With the geothermal ventilation system no any type of adverse effect on
pig’s average daily gain, feed intake and feed conversion efficiency.

Geothermal
ventilation loop have multiple use for example in Oregon zoo they had develop a
multilateral ground loop which provide a cool environment to bear and warm
environment for elephants (OZ, 2014).

A
study conducted at Chumathang, Himachal Pradesh, to know the energy cost per
unit exergy for parallel combination of a phase change system with a heating
system. At low flow rate and -5°(C) ambient temperature
cost per unit exergy were 0.32 and 0.69 (USD MJ-1 hr-1),
respectively (Chauhan, 2013).

Stein, (2013) reported that
University of Missouri, has developed a geothermal energy system for a large
turkey farm in that state. The project has been jointly funded by the US
Department of Energy as a demonstration project in partnership with the farm’s
owner. The system is being used both for brooding and grow-out. The project
team estimates that they will save on energy costs between 50 and 70 per cent.

It
has been concluded that a GHP system couldincrease the production performance
of broiler chicksdue to increased inside air quality of the broiler house.The
GHP system had lower CO2 and NH3 emissionswith lower
energy cost than the conventional heatingsystem for broiler chickens (Choiet
al.,2012).

            Jacobson, (2012) suggested that
there are cooling alternatives to the traditional evaporative systems used in
pig facilities in the Midwestern USA and other pig growing areas of the world
that could result in reduced energy and emissions per pound of pork produced
while still being economically viable. A geothermal system was evaluated as one
possible method to provide cooling for pig buildings that could provide an
effective and economicapproach to cooling pig facilities.

            In a
comparative study between the ground source heat pump(GSHP) heating and cooling
system, coal fired heating system(CFH), wet curtain fan cooling system(WCFC),
air conditioning found that initial investment of GSHP heating and cooling
system was higher than that of the CFH system integrated with WCFC system, the
relative operating cost of GSHP, CFH and AC was 0.94, 1.00, 0.98, respectively
(Wang et. al., 2012).

In
a case study of poultry farm in Syria came to a conclusion that coefficient of
performance of GSHP for heating and cooling were 6.2 and 10 respectively, while
corresponding values of ASHP were 4 and 4.3 only.  Also found that annual cost of GSHP is
reduced up to 38 per cent, 69.2 per cent, and 79.7 per cent as compared to
ASHP, coal heater combined with ASHP and diesel heater combined with ASHP,
respectively (Mohamad, 2012)

 

CONCLUSION

In recent era of energy crisis geothermal ventilation
system is a good alternative. Geothermal ventilation will reduce the greenhouse
effect by reducing the production of greenhouse gases like CFC and HCFC etc.
Geothermal ventilation reduces the emission of harmful gasses and also risk of
microbial contamination into the farm shed.Geothermal ventilation provides natural
air with improved quality which is favourable to maintain animal growth and
health. It is efficient, safe, flexible source of renewable energy.Geothermal
ventilation system is best alternative to create favourable microclimatic
condition in animal house during adverse climate.