The document describes the design of an efficient evaporative air cooler system called Combiswitch. The Combiswitch is connected to existing cooler systems and controls the cooling effect based on humidity variations. It uses a humidity sensor and microcontroller to automatically govern the water pump speed, maintaining optimum humidity levels for human comfort while minimizing water and energy usage. The system provides improved performance over existing evaporative coolers in high humidity environments.

1. EFFICIENT
EVAPORATIVE AIR
COOLER SYSTEM
Akshay Lawange
jawaharlal darda inst of engg and tech
Final year EXTC

2. INTRODUCTION
 WE ARE PLANNING TO DESIGN A NEW PRODUCT
THAT CAN BE USED IN EXISTING DOMESTIC COOLER
SYSTEMS.
 THE PRODUCT IS A HUMIDITY BASED EFFICIENT
EVAPORATIVE COOLER SYSTEM WHICH MAINTAINS
THE HUMIDITY RANGE WITHIN OPTIMUM LEVELS
SUITABLE FOR THE HUMAN BODY.
 THE PRODUCT IS NAMED AS COMBISWITCH.

3. WHAT IS HUMIDITY?
 HUMIDITY IS SOMETHING WE HEAR ABOUT DAILY IN
WEATHER REPORTS.
 ABSOLUTE HUMIDITY IS THE MASS OF WATER VAPOUR
DIVIDED BY THE MASS OF DRY AIR IN A VOLUME OF AIR
AT A GIVEN TEMPERATURE.
 RELATIVE HUMIDITY IS THE RATIO OF THE CURRENT
ABSOLUTE HUMIDITY TO THE HIGHEST POSSIBLE
ABSOLUTE HUMIDITY( WHICH DEPENDS ON THE
CURRENT AIR TEMPERATURE)

4. HUMIDITY AND HUMAN BODY
 WHEN THE RELATIVE HUMIDITY IS HIGH, WE FEEL
MUCH HOTTER THAN ACTUAL TEMPERATURE.
 IF THE RELATIVE HUMIDITY IS LOW, WE FEEL
MUCH COOLER THAN THE ACTUAL TEMPERATURE
BECAUSE OUR SWEAT EVAPORATES EASILY COOLING
US OFF.
 THE HEAT INDEX IS AN INDEX THAT COMBINES AIR
TEMPERATURE AND THE RELATIVE HUMIDITY IN AN
ATTEMPT TO DETERMINE THE HUMAN-PERCIEVED
EQUIVALENT TEMPERATURE.
 PEOPLE TEND TO FEEL MOST COMFORTABLE AT A
RELATIVE HUMIDITY OF ABOUT 45 %.

5. EXISTING EVAPORATIVE COOLER
SYSTEMS
 AN EVAPORATIVE COOLER IS A DEVICE THAT COOLS AIR
THROUGH THE EVAPORATION OF WATER.
 EVAPORATIVE COOLING DIFFERS FROM TYPICAL AIR
CONDITIONING SYSTEMS WHICH USE VAPOUR COMPRESSION
OR ABSORPTION REFRIGERATION CYCLES.
 EVAPORATIVE COOLING WORKS BY EMPLOYING WATER‟S
LARGE ENTHALPY OF VAPORIZATION.
 THE TEMPERATURE OF DRY AIR CAN BE DROPPED
SIGNIFICANTLY THROUGH THE PHASE TRANSITION OF LIQUID
WATER TO WATER VAPOUR, WHICH REQUIRES MUCH LESS
ENERGY THAN REFRIGERATION.

7. WORKING OF EVAPORATIVE
COOLERS:
 AN EVAPORATIVE COOLER PRODUCES EFFECTIVE COOLING
BY COMBINING A NATURAL PROCESS OF EVAPORATION WITH A
SIMPLE, RELIABLE AIR MOVING SYSTEM.
 FRESH OUTSIDE AIR IS PULLED THROUGH MOIST PADS
WHERE IT IS COOLED BY EVAPORATION AND CIRCULATED
THROUGH A HOUSE BY A BLOWER.AS THIS HAPPENS, THE
TEMPRATURE OF THE OUTSIDE AIR CAN BE LOWERED AS
MUCH AS 30 DEGREES.
THE NEXT FIGURE SHOWS THE WORKING OF EVAPORATIVE
COOLER .

9. DISADVANTAGES OF THE EXISTING
SYSTEM:
 HIGH HUMIDITY CONDITIONS DECREASE THE COOLING
EFFICIENCY OF THE EVAPORATIVE COOLER.
 UNDER HIGH HUMIDITY ENVIRONMENTS, WHEN THE
RELATIVE HUMIDITY IS AROUND 80%-90%, THE ELECTRICAL
SYSTEMS WILL EVENTUALLY UNDERGO CORROSION AND
MOISTEN SURFACES.
 IT RELIES HEAVILY ON UNINTERRUPTED WATER SUPPLY
TO FUNCTION. THUS, WE HAVE TO ENSURE THAT THE
WATER TANK IS FILLED AND ITS PADS ARE ALWAYS WET.

10. PROBABLY BECAUSE EVAPORATIVE COOLERS ADD MOISTURE
TO THE AIR AND BLOW IT AROUND,THEY ARE SOMETIMES
KNOWN AS “SWAMP COOLER”.
EVAPORATIVE COOLERS CAN WORK WONDERFULLY
WELL,PROVIDED THE OUTSIDE AIR THEY ARE DRAWING IN, IS
DRY AND DESERT LIKE .
AS THE HUMIDITY INCREASES, HOWEVER, THE ABILITY FOR
THEM TO COOL THE AIR EFFECTIVELY DECREASES.
SIMPLY PUT, EVAPORATIVE COOLERS ARE NOT DESIGNED TO
WORK IN HIGH HUMIDITY CONDITIONS.

11. MOTIVATION
 LOW HUMIDITY CAUSES RESPIRATORY ILLNESS OR
CERTAIN ALLERGIES, BREATHING PROBLEMS AND MAY
CAUSE JOINT PAIN.
 ON THE OTHER HAND, HIGH HUMDITY
ENCOURAGES BACTERIA, MOULD, AND FUNGUS
GROWTH.
 TO DESIGN SUCH A SYSTEM WHICH CAN WORK AT
RELATIVE HUMIDITY LEVELS AND TO MAINTAIN
OPTIMUM RANGE OF HUMIDITY.
 TO OVERCOME THE DEFECTS IN EXISTING SYSTEM.

12. PROBLEM STATEMENT:
 TO DESIGN AN ENERGY EFFICIENT DEVICE
WHICH WHEN CONNECTED TO AN EXISTING
COOLER SYSTEM CONTROLS THE COOLING EFFECT
BASED ON VARIATION OF HUMIDITY.
 THE PRODUCT SHOULD BE ECONOMICAL IN
HARDWEAR REALISATION AND EFFICIANT IN POWER
SAVING.

13. WE INTEND
TO :
 CONNECT EVAPORATIVE COOLER TO ELECTRIC POWER BY
THE COMBISWITCH WHICH ENABLES ITS HUMIDITY SENSOR
TO GET INTO OPERATION.
 IT AUTOMATICALLY GOVERNS THE SPEED OF THE WATER
PUMP, THEREBY THE RATE OF EVAPORATION OF THE
WATER POURED ON THE COOLER PADS.
 THIS IN TURN AFFECTS MAXIMUM COOLING WITH
MINIMUM WATER, ECONOMICALLY.

14. THE ROADMAP
PHASE 1:
 Developing idea
 Identifying components
 Design of circuit diagram
 Components selection and testing
 Program simulation and debugging
 Breadboard testing of circuit
 PCB design(compact)

15. PHASE 2:
 Design of Combiswitch
 Enclosing the components in Combiswitch
 Space optimization
 System integration
 Running the product
 Measuring the performance
 Giving the product look
 Manual preparation

16. INTERNAL CONNECTIONS OF COOLER

17. WORKING :
 HUMIDITY SENSOR SENSES THE HUMIDITY AND
GIVES THE EQUIVALENT OUTPUT TO THE MCU 8051.
 MCU 8051 SAMPLES THIS OUTPUT OF SENSOR
AND TAKES CERTAIN DECISION AS PER THE
PROGRAMMING .
IF THE HUMIDITY IS VERY HIGH THE DEHUMIDIFIER
DEHUMIDIFIES THE AIR AND ENHANCES THE
COOLONG EFFECT.
THE WATER LEVEL CONTROLLER INDICATES THE
LEVEL OF WATER IN THE TANK AND IF IT IS BELOW A
PREDEFINED LEVEL THE MOTOR AUTOMATICALLY
TURNS OFF.
LCD DISPLAY IS ALSO INTERFACED TO MCU 8051
FOR DISPLAYING THE RELATIVE HUMIDITY AND
VERIFYING THE RESULTS.

18. CONTD……….
IF HUMIDITY SENSED BY THE SENSOR IS LESS,
THE PUMP IS SWITCHED ON AND SPEED OF FAN IS INCREASED.
HENCE HUMIDITY OF THE ROOM STARTS TO INCREASE.
WHEN IT REACHES OPTIMUM VALUE THE SPEED OF THE MOTOR
IS
DECREASED AND THUS THE COOLING IS MONITORED.
THUS OUR NEW SYSTEM IS CLOSED LOOP CONTROL SYSTEM WHERE
THE PARAMETER WHICH ARE CONTROLLED ARE RELATIVE HUMIDITY
AND WATER LEVEL.

19. MICROCONTROL
LER :
• High-performance, Low-power Atmel® AVR® 8-bit
Microcontroller
High Endurance Non-volatile Memory segments
– 16 Kbytes of In-System Self-programmable Flash program
memory
– 512 Bytes EEPROM
– 1 Kbyte Internal SRAM
Peripheral Features
– Two 8-bit Timer/Counters with Separate Prescalers and
Compare Modes
– One 16-bit Timer/Counter with Separate Prescaler, Compare
Mode, and Capture
Mode
– Real Time Counter with Separate Oscillator
– Four PWM Channels
– 8-channel, 10-bit ADC
8 Single-ended Channels
7 Differential Channels in TQFP Package Only
2 Differential Channels with Programmable Gain at 1x, 10x, or
200x

20. PIN DIAGRAM :

22. HUMIDITY SENSOR
A HUMIDITY SENSOR ALSO CALLED AS HYGROMETER
MEASURES AND REGULARLY REPORTS THE RELATIVE
HUMIDITY IN THE AIR.
THIS MEANS THAT IT MEASURES BOTH AIR
TEMPERAURE AND MOISTURE.
THE MOST COMMON TYPE OF HUMIDITY SENSOR USES
WHAT IS CALLED „CAPACITIVE MEASUREMENT‟.
THE SENSOR ITSELF IS COMPOSED OF TWO METAL
PLATES WITH A NON-CONDUCTIVE POLYMER FILM
BETWEEN THEM.
THE FILM COLLECTS MOISTURE FROM THE AIR AND
THE MOISTURE CAUSES MINUTE CHANGES IN THE
VOLTAGE BETWEEN THE TWO PLATES.

23. SENSORS TO BE USED
SHT1x (INCLUDING SHT10, SHT11 AND SHT15)
 SENSIRION‟S FAMILI OF SURFACE MOUNTABLE RELATIVE
HUMIDITY AND TEMPERATURE SENSORS.
 THE SENSORS INTEGRATE SENSOR ELEMENTS PLUS
SIGNAL PROCESSING ON A TINY FOOT PRINT AND PROVIDE
A FULLY CALLIBRATED DIGITAL OUTPUT.
 A UNIQUE CAPACITIVE SENSOR ELEMENT IS USED FOR
MEASURING RELATIVE HUMIDITY WHIL E TEMPERATURE IS
MEASURED BY A BAND-GAP SENSOR.
 BOTH SENSORS ARE SEAMLESSLY COUPLED TO A 14-BIT
ANALOG TO DIGITAL CONVERTER AND A SERIAL INTERFACE
CIRCUIT.

24.  THE CHANGES IN THE VOLTAGE ARE THEN CONVERTED
INTO DIGITAL READINGS SHOWING THE AMOUNT OF
MOISTURE IN THE AIR.

25. INTERFACING SHT1x TO
MICROCONTROLLER

26. CIRCUIT

27. FLOWCHART
START
INITIALIZE PORTS A AND D
INITIALIZE ADC: ADCSRA= 87H AND ADMUX = 60H
B
START CONVERSION: ADSC = 1
NO IS ADIF
= 1?
YES
VALUE = ADCH
A

28. A
IS
VALUE<12
2
(55% RH)
NO YES
LED OFF LED ON
RELAY OFF RELAY ON
B

29. FRONT PANEL OF
COMBISWITCH

30. COST ESTIMATION
SR. NO. COMPONENT COST(in Rs.)
1 HUMIDITY SENSOR 430/-
2 MICROCONTROLLER ATMEGA 16 150/-
3 ELECTROMECHANICAL RELAY 20/-
4 ULN 2803 15/-
5 VOLTAGE REG 7805 10/-
6 PCB 15/-
7 CAPACITORS-3 NO’S 5/-
8 RESISTORS 2/-
9 CRYSTAL 10/-
10 PCB FABRICATION 50/-
11 BATTERY-2 NO’S 50/-
12 SWITCH BOX 35/-
13 SWITCHES 10/-
14 WIRES 20/-
TOTAL 772/-
GROSS TOTAL 800/-

31. ADVANTAGES OF THE NEW SYSTEM:
 FIRST, THE NEW SYSTEM IS A LOT LESS COSTLY TO
INSTALL WHEN COMPARED WITH REFRIGERATED AIR
CONDITIONERS, THEREBY SETTING UP A COOLER COSTS ONLY
ABOUT ONE EIGHTH TO A HALF OF THAT OF REFRIGERATED
AIR CONDITIONERS.
 OPERATING IT IS ALSO CHEAPER, ACCOUNTING FOR JUST
A FOURTH OF WHAT IS EXPENDED ON REFRIGERATED AIR.
 THE BENEFITS OF BOTH FAN AND MOTOR COMBINED
WITH ADVANCED ELECTRONIC CONTROLS, MANAGE AND
MONITOR THE MOTOR TO ENSURE THAT THE SYSTEM RUNS
AT OPTIMUM EFFICIENCY AT ALL TIMES.
 THE SYSTEM IS SO SMART THAT IT EVEN ADJUSTS THE
MOTOR SPEED AUTOMATICALLY TO COPE WITH DIFFERENT
HUMIDITY LEVELS.

32. FUTURE SCOPE
 In the future designs of the evaporative air coolers, the combiswitch
can be integrated within the cooler structure itself.
 Using a RF module, the combiswitch can be controlled through a
remote control, which will make it even more user-friendly.
 An LCD displaying the relative humidity and the temperature may
also be incorporated within such an advanced cooler.
 An additional control may be provided for the blower speed control.
 A dehumidifier may also be employed to improve the performance
of the cooler system.

33. THANK YOU !!