Presentation on Thermal Pollution

3. • Thermal Pollution is a form of environmental pollution.
• It refers t o an increase of t emperat ure in a body
of wat er due t o human or environment al cause.
• In a general way, it is the degradation of water quality by any
process that changes ambient water temperature.
• The dumping of heated gases or waste heat
(often from electrical generating plants) into the air
or water to cause an undesirable change in natural
environment.
• Industrial discharge of heated water into a river, lake, or other
body of water, causing a rise in temperature that endangers
aquatic life.

4. • Heat producing industries i.e., thermal power plants, nuclear power
plants, refineries, steel mills etc., are the major sources of thermal
pollution.
• Power plants utilize only 1/3 of the energy provided by fossil fuels for
their operations. Remaining 2/3 is generally lost in the form of heat to
the water used for cooling.
• Cold water, generally, is drawn from some nearby water-body, passed
through the plant and returned to the same water body, with
temperature 10-16°C higher than the initial temperature.
• Raw materials for productivity (organic and inorganic products)
undergo different chemical reactions with several process.
• We can classify major sources that lead to thermal pollution to the
following categories:
1. Power plants creating electricity from fossil fuel
2. Water as a cooling agent in industrial facilities
3. Deforestation of the shoreline
4. Soil erosion
5. Agriculture sources

5. (i ) T he dissolved ox yg en cont ent of wat er is
decreased as t he solubilit y of ox yg en in wat er is
decreased at hig h t emperat ure.
(i i ) Hig h t emperat ure becomes a barrier for ox yg en
penet rat ion int o deep cold wat ers.
(i i i ) T ox icit y of pest icides, det erg ent s and chemicals
in t he effluent s increases wit h increase in
t emperat ure.
(i v) T he composit ion of flora and fauna chang es
because t he species sensit ive t o increased
t emperat ure due t o t hermal shock will be replaced by
t emperat ure t olerant species.
(v) Met abolic act ivit ies of aquat ic org anisms increase
at hig h t emperat ure and require more ox yg en,
whereas ox yg en level falls under t hermal pollut ion.
(vi ) Discharge of heated water near the shores can
dist urb spawning and can even kill young fishes.
(vii ) Fish mig rat ion is affect ed due t o format ion of
various t hermal zones.

6. 1.Cooling ponds
2.Spray Ponds
3.Cooling towers
The following methods can be employed for control
of thermal pollution:

7. • DEFINITION: Feeling of satisfaction with the surrounding
environment is called THERMAL COMFORT.
• Heat comfort is a state of equilibrium with the surroundings.
• Thermal neutrality is maintained when the heat generated by human
metabolism is allowed to dissipate.
• Satisfaction with the thermal environment is important for its own
sake and because it influences productivity and health.
• Maintaining thermal comfort for occupants of buildings or other
enclosures is one of the important goals of HVAC design engineers.

8. • For a given person at a given activity, clothing, and
environment, the heat balance is established by the
combination of mean skin temperature and sweat loss.
• These are called the COMFORT ZONES.
• Comfort zones have temperatures as follows:
22.8C<Effective temperature<26.1C
(summer)
20.0C<Effective temperature<23.9C
(winter)

9. • Personal factors:
Health, body
shape, activity
levels, clothing, psychol
ogy etc.
• General Factors: Air
temperature, relative
humidity.
• Localized factors: Air
movement, temperature
of floor, air
temperature variations
with heights.

10. • A n u r b a n h e a t i s l a n d i s a
m e t r o p o l i t a n a r e a t h a t i s
s i g n i f i c a n t l y w a r m e r t h a n i t s
s u r r o u n d i n g r u r a l a r e a s d u e t o
h u m a n a c t i v i t i e s .
•U s u a l l y h e a t i s l a n d s i n c i t i e s
h a v e a m e a n t e m p e r a t u r e t h a t i s
8 t o 1 0 d e g r e e s m o r e t h a n t h e
s u r r o u n d i n g r u r a l a r e a s .
• T h e t e m p e r a t u r e d i f f e r e n c e i s
g r e a t e r a t n i g h t t h a n i n t h e d a y
a n d l a r g e r i n w i n t e r t h a n i n
s u m m e r .
• T h e r e a s o n f o r m a x i m u m
t e m p e r a t u r e d i f f e r e n c e a t
n i g h t s a r e f o r t h e r e a s o n t h a t
t h e r u r a l a r e a s g e t s c o o l e d
f a s t e r t h a n t h e u r b a n a r e a s .

12. •Buildings with dark surfaces heat up more rapidly and require more cooling
from air conditioning, which requires more energy from power plants.
•They are usually very good at insulating, or holding in heat. This insulation
makes the areas around buildings warmer.

13. • The extent of heat island depends upon local
meteorological, locational and urban characteristics.
• The intensity of heat island depends upon population, clear sky, light
winds and vehicles in the city.
• The effect is best during evening.
• The positive effect of heat island are
• Growing season of plants increases
• early flowering in urban areas in winter than rural
• less need of space heating in winter
• less electricity consumption
• The negative effects of heat island are
• Increase energy consumption
• Increase in air pollution
• Effect on human health
• Effect on water bodies

15. • Solar radiation is radiant energy emitted by the sun, particularly
electromagnetic energy
• The spectrum of the Sun's solar radiation is close to that of a black
body with a temperature of about 5,800 K.
• The Sun emits EM radiation across most of the electromagnetic
spectrum.
• Although the Sun produces Gamma rays as a result of the nuclear
fusion process, these super-high-energy photons are converted to
lower-energy photons before they reach the Sun's surface and are
emitted out into space. As a result, the Sun does not emit gamma rays.
• The Sun does, however, emits
• X-rays
• UV rays
• Infrared rays
• Visible rays
• Radio waves
• The spectrum of nearly all solar electromagnetic radiation striking
the Earth’s atmosphere spans a range of 100 nm to about 1 mm.

16. • Ultraviolet C or (UVC) range, which spans a range
of 100 to 280 nm.This spectrum of radiation has
germicidal properties, and is used in germicidal
lamps. Small amount is beneficial forVitamin-D
production. Prolonged exposure causes health
effects.
• Ultraviolet B or (UVB) range spans 280 to 320 nm.
It is also greatly absorbed by the atmosphere, and
along with UVC is responsible for
the photochemical reaction leading to the
production of the ozone layer. It directly damages
DNA and causes sunburn, skincancer, eye damage.
• Ultraviolet A or (UVA) spans 320 to 400 nm.This
band was once held to be less damaging
to DNA, and hence is used in cosmetic artificial sun
tanning and PUVA therapy for psoriasis.
However, UVA is now known to cause significant
damage to DNA via indirect routes (formation
of free radicals and reactive oxygen species), and is
able to cause cancer.