Air Humidification - Technical, health and energy aspects by L. Nalini

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Information about Air Humidification - Technical, health and energy aspects by L. Nalini

Published on October 20, 2016

Author: CAREL_group

Source: slideshare.net

1. AIR HUMIDIFICATION Technical, health and energy aspects Luigi Nalini Lisbon, October 20th, 2016

2. IN CASE OF INTEREST, THE SLIDES SHOWN  TODAY MAY BE REQUESTED AT THE FOLLOWING  E‐MAIL ADDRESS: media.relations@carel.com

3. LIFE ON EARTH DEPENDS ON WATER ALL KNOWN LIFE FORMS DEPEND ON THE PRESENCE OF WATER THAT MAKES POSSIBLE THE METABOLIC PROCESSES. MANY OTHER SUBSTANCES AND PRODUCTS, BOTH ORGANIC AND INORGANIC, CONTAIN WATER THAT AFFECTS HEAVILY THEIR PHYSICAL, CHEMICAL AND DIMENSIONAL PROPERTIES. THE CONTENT OF WATER IN BODIES OR MATERIALS IS THE RESULT OF A BALANCE BETWEEN INTAKE AND LOSS AMONG THE BODIES THEMSELVES AND WHAT SURROUNDS THEM, INCLUDING THE ATMOSPHERE. ON A PLANETARY SCALE THIS BALANCE IS MAINLY DETERMINED BY THE HYDROLOGICAL CYCLE THAT CAUSES THE CONTINUOUS CHANGE OF STATE AND MOVEMENT OF WATER ON THE SURFACE OF THE EARTH AND ABOVE IT.

4. THE HYDROLOGICAL CYCLE THE PROVISION OF WATER NECESSARY FOR THE EXISTENCE OF LIFE AND THE CONSERVATION OF SUBSTANCES OR BODIES ON EARTH HAPPENS THANKS TO THE ATMOSPHERE THAT ABSORBS THE VAPOR ORIGINATED FROM THE LIQUID MASSES AND PROMOTES THE GENERATION OF CLOUDS WHICH THEN FALL UNDER LIQUID OR SOLID FORM TO THE GROUND.

5. THE DISTRIBUTION OF RAINWATER THROUGH THE RIVERS AND THE SOIL INFILTRATION, IS THE MAIN SOURCE OF HYDRATATION OF THE PLANT KINGDOM AND THUS OF ALL LIVING SPECIES, HOWEVER A SUBSTANTIAL PART OF WATER STANDS IN THE ATMOSPHERE IN THE FORM OF VAPOR, SPREADING ITS MOLECULES THROUGH THE AIR. THE CONTENT OF WATER VAPOR MOLECULES IN THE AIR IS DEFINED HUMIDITY. ANY AIR CONTAINING WATER VAPOR MOLECULES IS CALLED HUMID AIR.

6. THE CIRCULATION AND THE DISTRIBUTION OF WATER WITHIN THE HYDROLOGICAL  CYCLE ARE MADE POSSIBLE BY THE TWO MAJOR TRANSFORMATIONS:  EVAPORATION (PASSAGE FROM LIQUID STATE TO VAPOR STATE);  CONDENSATION (FROM VAPOR STATE TO LIQUID STATE). THE PASSAGE FROM ICE/SNOW INTO WATER AND VICE VERSA PLAYS AN IMPORTANT ROLE BUT NOT IMMEDIATELY TIED WITH THE HYDRATATION OF THE EARTH

7. ACCORDING TO THE MOLECULAR KINETIC THEORY, AS ANY ELEMENT WATER ASSUMES THE SOLID, LIQUID, GASEOUS STATE IN FUNCTION OF THE INTERNAL ENERGY OF ITS MOLECULES , WHICH OCCURS AS VIBRATIONAL, ROTATIONAL, TRANSLATIONAL MOTION AND RECIPROCAL COLLISIONS. TEMPERATURE IS A MEASURE OF THE AVERAGE INTERNAL ENERGY AND THEREFORE THE HIGHER THE TEMPERATURE, THE GREATER THE INTERNAL ENERGY OF THE WATER MOLECULES. IN LIQUID WATER THE INTERNAL ENERGY OF MOLECULES IS NOT HIGH ENOUGH TO BREAK THE RECIPROCAL ATTRACTION: UNLIKE SOLID ICE, IN WHICH MOLECULES MOVE AROUND THEIR FIXED POSITION, LIQUID WATER HAS A DEFINED VOLUME BUT NO CONSISTENCY AND THUS, DUE TO GRAVITY OR CAPILLARITY, TAKES THE SHAPE OF ITS CONTAINER. THE THREE PHYSICAL STATES OF WATER

8. UPON A SUFFICIENT ENERGY INPUT – UNDER HEAT FORM – THE MOLECULES OF LIQUID WATER INCREASE THEIR AVERAGE INTERNAL ENERGY; PART OF THEM REACH AN ENERGY LEVEL SUFFICIENT TO ENTER IN THE EVAPORATION PROCESS, OVERCOMING THE ATTRACTIVE FORCES OF THE BULK OF THE LIQUID, PASSING TO THE GASEOUS STATE AND SPREADING IN THE AVAILABLE SPACE AROUND. ON THE CONTRARY, IF THE MOLECULES OF WATER CONTAINED IN THE AIR TRANFER SOME HEAT (FOR EXAMPLE COMING IN CONTACT WITH A COLD SURFACE), THEIR INTERNAL ENERGY MAY BECOME INSUFFICIENT TO ENABLE THEM TO REMAIN AT THE GASEOUS STATE: IN THIS CASE TAKES PLACE THE CONDENSATION PROCESS IN WHICH THE VAPOR TURNS INTO LIQUID. EVAPORATION AND CONDENSATION OF WATER

9. THE AVERAGE KINETIC ENERGY OF VAPOR MOLECULES DETERMINES DIRECTLY THE MACROSCOPIC PRESSURE THEY EXERT OVER THE ADJACENT BODIES, IN PROPORTION TO THE NUMBER AND THE FORCE OF THE COLLISIONS. AS WELL AS THE INTERNAL ENERGY, ALSO VAPOR PRESSURE DEPENDS JUST ON TEMPERATURE. ENTERING INTO THE ATMOSPHERE THE VAPOR MOLECULES MUST «COMPETE» WITH THE PRESSURE EXERTED BY THE OTHER GASES: INFACT, ACCORDING TO THE GAS LAWS, THE INDIVIDUAL PRESSURE OF ANY GAS (CALLED ALSO PARTIAL PRESSURE) IN THE MIXTURE IS PROPORTIONAL TO ITS VOLUMETRIC FRACTION. THE DIAGRAM SHOWS THE PRESSURE EXERTED BY THE VAPOR MOLECULES vs TEMPERATURE JUST AT THE SURFACE OF LIQUID WATER (i.e.: 3170 Pa @ 25°C). THE SURFACE VAPOR PRESSURE, SINCE IN EQUILIBRIUM BETWEEN LIQUID AND VAPOR, IS THE MAXIMUM POSSIBLE AT THAT TEMPERATURE AND THEREFORE IS DEFINED SATURATION PRESSURE PVS. 0 5 10 15 20 25 30 35 40 45 50 14000 12000 10000 8000 6000 4000 2000 0 temperature ‐ °C Vaporpressure ‐Pa SATURATION PRESSURE VPS OF WATER vs TEMPERATURE 3170 WATER VAPOR PRESSURE

10. THE NUMBER OF MOLECULES OF WATER CONTAINED IN THE AIR IS PROPORTIONAL TO THE PARTIAL PRESSURE THEY EXERT. THE MAXIMUM QUANTITY IS GOT WHEN THE VAPOR PARTIAL PRESSURE EQUALS THE SATURATION PRESSURE VPS; IN THIS CASE, THE AIR IS SAID SATURATED WITH VAPOR. kPa20,5 76,6 0,97 3,17 0,07 101,3 22,6% 74% 1,33% 1,97% 0,11% 100%weight PROPORTION OF ATMOSPHERE MAIN COMPONENTS WITH  WATER VAPOR AT SATURATION WHEN TEMPERATURE = 25°C BUT, DIFFERENTLY FROM PERMANENT GASES (N2, O2, AR) WHOSE PERCENTAGE IS STABLE, WATER VAPOR CONCENTRATION VARIES WITH GEOGRAFIC LOCATION, TEMPERATURE AND WEATHER: IF THE CONTENT OF VAPOR IN THE AIR IS NOT ENOUGH FOR SATURATION, THE VAPOR PRESSURE PV IS ALSO LOWER THAN THE SATURATED PRESSURE PVS. THE RATIO BETWEEN THE ACTUAL PRESSURE AND THE SATURATED PRESSURE IS DEFINED RELATIVE HUMIDITY RH: RH = PV / PVS          [%] VAPOR PRESSURE OF WATER vs TEMPERATURE AND RH 0 1000 2000 3000 4000 5000 6000 0 5 10 15 20 25 30 35 40 temperature ‐ °C Vaporpressure ‐Pa 25 PVS = 3170 PV = 1270 VAPOR PRESSURE  DEFICIT ATMOSPHERIC PRESSURE (101,325 Pa) ATMOSPHERIC RELATIVE HUMIDITY

11. SOME “MISTERIOUS” STAINS OF MOLD IN THE CORNERS OF A HOUSE ARE GENERALLY CAUSED DURING COLD SEASONS JUST BY THE MIGRATION OF VAPOR FROM THE KITCHEN OR FROM THE BATHROOM WHERE IT IS GENERATED TO THE COLDER SPOTS WHERE IT CONDENSES. THE ATMOSPHERIC AIR IS A FUNDAMENTAL VEHICLE FOR THE TRANSPORTATION OF ACCORDING TO DALTON’S LAW EVERY GAS IN A MIXTURE BEHAVES INDEPENDENTLY OF THE OTHER ONES AS IT WAS ALONE AT ITS OWN PARTIAL PRESSURE. FOR THIS REASON IF TWO CONTIGUOUS AREAS HAVE AN UNEQUAL MOISTURE CONTENT, DUE TO THE PARTIAL PRESSURE DIFFERENCE THE VAPOR WILL PASS FROM THE SPACE WITH THE HIGHER MOISTURE CONTENT TO THE OTHER. WATER VAPOR MIGRATES THROUGH THE ATMOSPHERE MOISTURE AND FOR THE WATER BALANCE OF LIVING BEINGS AND BODIES OR MATERIALS – ORGANIC AND INORGANIC – WHOSE PROPERTIES ARE INFLUENCED BY THEIR WATER CONTENT NOT ONLY WITHIN CLOSED ENVIRONMENTS BUT ALSO IN IN VAST OUTDOOR SPACES AS IN DESERTIC AREAS WHERE RAINS ARE VERY RARE

12. THE TRANSFER OF MOISTURE WILL CONTINUE UNTIL THE TWO PRESSURES WILL EQUALIZE; DUE TO THE HUGE DISPARITY IN MASS, THE FINAL VAPOR PRESSURE IN THE ROOM WILL BECOME VERY SIMILAR TO THE EXTERNAL ONE, UNLESS THERE IS AN INDOOR PROCESS OF HUMIDITY CONTROL.0 5 10 15 20 25 30 35 40 25 20 15 10 5 0 DRY BULB TEMPERATURE ‐ °C ABS. HUMIDITY ‐gV/kgA VAPOR PARTIAL PRESSURE ‐KPA 1 2 3 0 0,49 2,5 1,5 3,5 2,53 15,9 3,0 24 Win Wout Sin Sout 22 VAPOR MIGRATES FROM INDOOR TO OUTDOOR AND VICEVERSA IF THERE IS A DIFFERENCE IN PARTIAL PRESSURES, THE MIGRATION OF VAPOR TAKES PLACE ALSO FROM AN ENCLOSED SPACE TO THE OUTDOOR AIR OR VICEVERSA THROUGH CRACKS – OFTEN UNNOTICED – ON BUILDING WALLS, DOORS, WINDOWS. HOWEVER IF THE TEMPERATURE OF THE TWO AMBIENTS ARE DIFFERENT, ALSO RELATIVE HUMIDITIES WILL BE AFFECTED. AS SHOWN IN THE ABOVE DIAGRAM, THE INDOOR RELATIVE HUMIDITY WILL NORMALLY BE DRIVEN TO HIGH VALUES IN SUMMER AND TO LOW ONES IN WINTER: BEYOND ACCEPTABLE LIMITS A CLIMATIC CONTROL SYSTEM BECOMES NECESSARY

13. STRATUM CORNEUM STRATUM GRANULOSUM STRATUM SPINOSUM WATER WATER TRASPIRATION OF ANIMAL EPIDERMIS TRANSPIRATION OF WOODTRASPIRATION OF  VEGETAL CELLS THE WATER CONTAINED IN ANY BODY OR MATERIAL HAS A SURFACE VAPOR PRESSURE EQUAL TO THE SATURATION VALUE PVS AT ITS TEMPERATURE. IF THE SURROUNDING AIR HAS A LOWER VAPOR PRESSURE, AN EVAPORATION OF WATER FROM THE BODY OR MATERIAL INTO THE AIR WILL START. ON THE OPPOSITE, THE PRESSURE DIFFERENCE WILL CAUSE THE TRANSFER OF VAPOR FROM THE AIR INTO THE BODIES OR MATERIALS THAT ABSORB IT. THE BELOW DRAWINGS SHOW THE «TRANSPIRATION» OF SOME ORGANIC MATTERS VAPOR MIGRATES FROM BODIES TO AIR AND VICEVERSA

14. DRY BULB TEMPERATURE ‐ °C VAPOR PARTIAL PRESSURE ‐KPA 1 2 3 2,5 1,5 3,5 20 25 30 35 40 25 20 15 10 5 ABS. HUMIDITY ‐gV/kgA CAUTION: HEAT CRAMPS AND  HEAT EXHAUSTION POSSIBILE  DANGER: HEAT CRAMPS AND  HEAT EXHAUSTION LIKELY PROBABLE HEAT STROKE DUE TO METABOLISM, HUMAN BODY GENERATES HEAT THAT, IN ORDER TO KEEP THE INTERNAL TEMPERATURE AT 36‐37°C, MUST BE NECESSARILY RELEASED: OUR PERCEPTION OF "HOT" OR "COLD" IS CAUSED BY THE CAPABILITY TO TRANSFER THE METABOLIC HEAT RATE MORE THAN BY ENVIRONMENTAL CONDITIONS. AS AMBIENT TEMPERATURE RAISES, THE HEAT TRANSFERRED BY CONVECTION OR RADIATION DECREASES AND OUR BODY SPONTANEOUSLY SWEATS HUMAN BODY PERCEIVES INDIRECTLY HIGH RELATIVE HUMIDITY UPON AN INCREASE OF HUMIDITY, SWEATING GROWS CREATING A SENSE OF UNEASE WITH NO BENEFIT. BEYOND CERTAIN TEMPERATURE/HUMIDITY LIMITS THE METABOLIC HEAT CANNOT BE RELEASED, CAUSING A SEVERE RISK OF A "HEAT STROKE" AND EVEN PUTTING AT RISK THE SURVIVAL. SO TO IMPROVE THE HEAT DISSIPATION THROUGH EVAPORATION.

15. BEING NOT EQUIPPED WITH SENSORY RECEPTORS SUITABLE TO FEEL DIRECTLY THE MOISTURE CONTENT OF THE AIR ‐ WHICH, IN ADDITION, IS FULLY TRANSPARENT ‐ HUMAN BODY IS LESS SENSITIVE TO LOW RELATIVE HUMIDITY. LOW HUMIDITY IS MOSTLY PERCEIVED ONLY FOR ITS SIDE EFFECTS THAT, ALTHOUGH POSSIBLY UNNOTICED IN THE SHORT TERM, COULD BE OBSERVED AFTER A CERTAIN PERIOD OF TIME; HOWEVER THE CONSEQUENCES CAN BE UNPLEASANT AND OFTEN HARMFUL ECONOMICALLY, TECHNICALLY AND PATHOLOGICALLY. LET US FOCUS ON THE EFFECTS OF LOW ENVIRONMENTAL RELATIVE  HUMIDITY, ON THE RECOMMENDED MINIMUM LIMITS IN THE VARIOUS  AMBIENTS AND CIRCUMSTANCES AND ON THE DEVICES USED TO FACE IT.   LIMITED SENSIBILITY OF HUMAN BODY TO LOW RELATIVE HUMIDITY

16. normal nasal mucosa irritated nasal mucosa OVER TIME, EXPOSURE TO LOW HUMIDITY CAN DRY OUT THE MUCUS MEMBRANES LOCATED IN THE NOSE AND THROUGH THE RESPIRATORY TRACT, WHICH ARE A NATURAL BARRIER TO INFECTION: BECOMING DRY, THEY LOSE THEIR ELASTICITY AND CRACK GIVING A DIRECT PATH FOR GERMS AND BACTERIA TO ENTER THE BLOODSTREAM. MOREOVER, DRY AIR DRAWS MOISTURE OUT OF THE SKIN CAUSING SMALL CRACKS ON ITS SURFACE AND PROVIDING AN ENTRYWAY FOR POTENTIAL DANGEROUS PATHOGENS. (GUGGENBICHLER ET AL., 2007) CARRIED OUT EXPERIMENTAL AND CLINICAL STUDIES AND CONCLUDED THAT FOR A GOOD MECHANICAL CLEARANCE OF THE AIRWAYS A HUMIDITY OF AT LEAST 30% ( BETTER 45%) IS REQUIRED. EFFECT OF LOW HUMIDITY IN HEALTH AND WELLNESS germs Rough, cracked,  pertially inflamed skin due to damaged barrier corneal layer lipids (fats) spinous layer basal layer ONE OF THE FIRST COMPLAINTS STATED BY PERSONS EXPOSED TO PROLONGED DRY AIR IS THE IRRITATION OF THE EYES ARISING IN CASE OF A BREAKDOWN OF THE TEAR FILM. LOW HUMIDITY IS ONE OF THE REASONS PEOPLE MAY BECOME SICK. THIS IS IMPORTANT PARTICULARLY FOR ESPECIALLY EXPOSED PERSONS SUCH AS PEOPLE IN HOSPITALS AND NURSING HOMES.

17. EFFECT OF LOW HUMIDITY ON WOOD AND PAPER MANY SUBSTANCES AND PRODUCTS CONTAIN WATER THAT AFFECTS THEIR PHYSICAL AND DIMENSIONAL PROPERTIES. THE LENGTH OF WOOD TANGENTIAL FIBRES INCREASES APPROX 0,04% PER %RH THUS, IF RH VARIES FROM 40% TO 50%, A WOODEN BOARD OF 500 mm LENGHTENS OF 2 mm. A RAPID CHANGE OF THE WATER CONTENT – AS OCCURS WHEN water content ‐% weight 10% 30% 50% 70% 90% 0 5 10 15 20 25 air relative humidity @ 20°C WOOD PAPER THE AIR HUMIDITY IS FAR FROM THE BALANCE WITH THE WOOD ‐ IMPLIES DIMENSIONAL VARIATIONS WHICH CAN LEAD TO THE BOWING OF THE BOARDS UP TO GET A CRACKING. THE CONTAINMENT OF THE AMBIENT RELATIVE HUMIDITY BETWEEN 35% AND 55% IS RECOMMENDED FOR ITS LOWER INFLUENCE ON WATER CONTENT IN THESE MATERIALS. REGARDING PAPER, A CHANGE OF RELATIVE HUMIDITY OF 10% IMPLIES A DIMENSIONAL VARIATION BETWEEN 0.1% AND 0.2%: ON A A4 SHEET IT MEANS NOT LESS THAN ½ mm. IN ADDITION, IN A STACK OF PAPER OR IN A BOOK THE VARIATION IN LENGTH TAKES PLACE INITIALLY IN THE PERIMETER PART, AND ONLY AFTER A LONGER TIME IN THE CORE, GIVING RISE TO FOLDING AND CORRUGATION OF THE SHEETS: THUS, BESIDES THE ABSOLUTE VALUE, THE RELATIVE HUMIDITY STABILITY IS VERY IMPORTANT. Pressroom = 75% RH Paper stack = 50% RH Pressroom = 35% RH Paper stack = 50% RH TIGHT EDGES WAVY EDGES

18. GENERALLY A HUMIDITY LEVEL BETWEEN 40% AND 60% IS MOSTLY SUITABLE FOR HUMAN COMFORT AND TECHNICAL PROCESSES (WITH SEVERAL EXCEPTIONS AS IN THE CONSERVATION OF MANY FOODS AND SUBSTANCES REQUIRING HIGHER VALUES). HOWEVER AIR HUMIDIFICATION IS AN ENERGY CONSUMING PRACTICE BECAUSE THE EVAPORATION OF 1 kg OF WATER REQUIRES AN INPUT OF APPROX 0,72 kWh (THE SAME REQUIRED TO RIDE BY BIKE 25 km IN ONE HOUR). IN ANY APPLICATION THE MINIMUM RELATIVE HUMIDITY THRESHOLD SHOULD BE A COMPROMISE BETWEEN THE ACTUAL NEEDS – PREVENTING MOISTURE DROPPING BELOW POTENTIALLY HARMFUL LEVELS ‐ AND THE RELEVANT COST INCURRED. THE MOST INFLUENTIAL CONSEQUENCES OF A LOW RELATIVE HUMIDITY ON OUR LIVES AND COMMON ACTIVITIES ARE: 1) THE ABSORPTION BY THE AIR OF THE WATER CONTAINED IN LIVING BEINGS AND IN MATERIALS, PARTICULARLY THE ORGANIC ONES; 2) THE BUILD‐UP OF STATIC ELECTRICITY WITH A RESULTING "SHOCK" FOR INVOLVED PEOPLE OR DAMAGES IN OBJECTS AND PRODUCTS. MINIMUM RELATIVE HUMIDITY THRESHOLD IS A COMPROMISE

19. THE SENSITIVITY OF MATERIALS TO ENVIRONMENTAL HUMIDITY IS ONE OF THE MAIN CAUSE OF DETERIORATION OF ARTWORKS MADE WITH HYGROSCOPIC MATERIALS. DIMENSIONAL ALTERATIONS MAY GENERATE CRACKS IN WOODEN SCULPTURES AND IN ANTIQUE FURNITURE OR IN MANUSCRIPTS WITH LOSS OF ELASTICITY AND BRITTLENESS. MATERIALS LIKE OIL, GESSOES, TEMPERA PAINTS HAVE A LOWER RESPONSE TO AIR RELATIVE HUMIDITY BRINGING TO CRAQUELURES IN PAINTINGS ON WOOD OR ON FRAMED CANVAS IN THE CASE OF WIDE CHANGES IN AMBIENT CONDITIONS. ACCORDING TO THE GUIDELINES OF THE SMITHSONIAN MUSEUM CONSERVATION INSTITUTE THE RELATIVE HUMIDITY FOR EXHIBITION AND STORAGE SPACES SHOULD BE INCLUDED BETWEEN 45% AND 55%, IN ANY CASE NOT LOWER THAN 37%. EVEN MORE IMPORTANT IS THAT HUMIDITY FLUCTUATIONS IN THE SHORT TERMS SHOULD NOT EXCEED A DEFINED TOLERANCE (TYPICALLY ± 5%). EFFECT OF LOW HUMIDITY IN ART GALLERIES, MUSEUMS, LIBRARIES “LA GIOCONDA” BY LEONARDO DA VINCI PAINTING ON POPLAR TABLE (LOUVRE) FRENCH WOOD SCULPTURE  (16TH CENTURY) PAINTING ON CANVAS  (19TH CENTURY)

20. EFFECT OF LOW HUMIDITY IN FOODSTUFF PRESERVATION TEMPERATURE AND RELATIVE HUMIDITY ARE FUNDAMENTAL FACTORS FOR A PROPER FOOD CONSERVATION. FRESH MEATS SHOULD BE STORED AT A TEMPERATURE NOT HIGHER THAN 2°C WITH A RELATIVE HUMIDITY AROUND 70%; A HIGHER HUMIDITY WOULD BE RISKY FOR A MICROORGANISMS GROWTH, BUT A LOWER ONE WOULD CAUSE A LOSS OF WEIGHT. THE MATURATION OF RAW HAMS OR DRY SAUSAGES REQUIRES CONTROLLED AIR HUMIDITY, STARTING FROM 90–95% AND, AFTER A CERTAIN PERIOD, FINALIZING THE PROCESS AT 70–75% AT 6‐10°C. A LOWER RELATIVE HUMIDITY WOULD CAUSE A COSTLY LOSS OF WEIGHT: THE WATER CONTAINED IN A PATANEGRA HAM MAY COST MORE THAN 100 €/LITER !! FRUITS AND VEGETABLES OPTIMAL STORAGE TEMPERATURE IS AROUND 2‐4°C WITH A HUMIDITY HIGHER THAN 90% (WITH EXCEPTIONS LIKE BANANAS, MELONS, CITRUS, PINEAPPLES AND OTHERS REQUIRING 10‐15°C AND A SLIGHTLY LOWER RH). ALSO THE STABILITY OF THERMOHYGROMETRIC CONDITIONS IS VERY IMPORTANT: A FREQUENT FLUCTUATION EVEN OF FEW °C OR HUMIDITY PERCENT PROVOKES WATER ASBORBING/DESORBING CYCLES FROM FOOD THROUGH CELL MEMBRANES WHICH CAUSES A SORT OF «FATIGUE» WITH A FASTER VISUAL AND QUALITY DETERIORATION.

21. EFFECT OF LOW HUMIDITY IN WINERY CELLARS  THE HUMIDIFICATION OF THE WINE CELLAR IS CRUCIAL BOTH DURING THE AGING OF WINE IN OAK BARRELS AND DURING STORAGE OF THE BOTTLES PLACED HORIZONTALLY. THE WINE WITHIN BOTTLES OR WITHIN BARRELS HAS A VAPOR PRESSURE EQUAL TO THE SATURATION VALUE HOWEVER THE CELLAR, ALTHOUGH AT THE SAME TEMPERATURE, IS NORMALLY FAR FROM 100% RELATIVE HUMIDITY: THUS, DUE TO PRESSURE DIFFERENCE, WATER VAPOR IS PUSHED TO ESCAPE THROUGH THE BOTTLE CORK OR THROUGH THE BARREL STAVES, PARTICUARLY IF THEY ARE NOT PERFECTLY TIGHT. IN ORDER TO MINIMIZE THE RISK TO DEHYDRATE AND DRY THE CORKS OR TO DESSICATE THE BARREL STAVES, IN WHICH CASE THE WINE WOULD EVAPORATE AND LET AIR ENTER ALTERING THE ORGANOLEPTIC PROPERTIES AND THE STRUCTURE OF THE WINE, IN A WINE CELLAR THE RELATIVE HUMIDITY SHOULD BE MAINTAINED AT 75%‐80%.

22. EFFECT OF LOW HUMIDITY ON WATER‐BORNE PAINTING COATINGSTHE USE OF WATER‐BASED COATINGS IS INCREASING ‐ PARTICULARLY IN AUTOMOTIVE AND AEROSPACE INDUSTRIES ‐ DUE TO LEGISLATION ON THE EMISSION OF VOC (VOLATILE ORGANIC COMPOUND) REPLACING MANY SOLVENT‐BASED COUNTERPARTS. HUMIDITY AND TEMPERATURE HAVE A SIGNIFICANT EFFECT ON HOW FAST WATER‐BORNE PAINT FLASHES OFF: THE WATER IS REMOVED FROM THE SURFACE OF THE PAINT VIA EVAPORATION, MIGRATING TO THE SURFACE UNTIL ALL OF IT HAS RISEN TO THE SURFACE AND EVAPORATED. THE TIME IN WHICH THE COATING IS DRY IS BASED ON THE AMOUNT OF WATER TO BE REMOVED AND THE EVAPORATION RATE, DEPENDENT UPON THE VAPOR PRESSURE DIFFERENCE BETWEEN THE WATER IN THE COATING AND THE AIR HUMIDITY IN ADDITION TO AIR VELOCITY. THE FINAL QUALITY IS BASED ON THE THERMOHYGROMETRIC CONTROL OF THE AIR RECIRCULATED IN THE SPRAY BOOTH ALL OVER THE YEAR, IRRESPECTIVE OF SEASONAL CONDITIONS. THE DESIGN RELATIVE HUMIDITY (50‐70%) DEPENDS ON THE PAINTING MATERIAL AND THE PROCESS; THE ACCURACY REQUIRED FOR HUMIDITY CONTROL IS AS LOW AS 2‐3%. High humidity causes an excessive diluition of the enamel deposited onthe body and formation of minuscule blister of liquid Low humidity causes an early evaporation of the water contained in the paints, so fluidity and covering capacity decrease

23. STATIC ELECTRICITY IS USUALLY CAUSED WHEN CERTAIN MATERIALS ARE RUBBED AGAINST EACH OTHER; IT IS ALSO CAUSED WHEN MATERIALS ARE PRESSED AGAINST EACH OTHER AND PULLED APART: THIS CHARGE MAY BE TRANSFERRED FROM THE MATERIAL TO NEXT GROUNDED OBJECT, CREATING AN ELECTROSTATIC DISCHARGE (ESD) WITH A SPARK. BEYOND THE MATERIALS, THE AMOUNT OF CHARGE IS AFFECTED BY THE AREA OF CONTACT, THE SPEED OF SEPARATION AND RELATIVE HUMIDITY. IN DRY AIR, WHERE THE IMBALANCED CHARGES HAVE NOWHERE TO GO, TYPICAL VOLTAGE LEVELS MAY EASILY ARRIVE TO 30.000‐ 40.000 VOLTS. TYPICAL ENERGY RELEASED BY A SPARK RARELY EXCEEDS 160 mJ WHICH, WHILE WELL BELOW THE RISKY LIMIT OF 5 J, CAUSES ANYWAY PHISICAL AND EMOTIONAL TROUBLES TO PEOPLE. AN ESD WITH A VOLTAGE AS LOW AS 15‐30 V CAN CAUSE VERY OFTEN A DESTRUCTIVE DAMAGE TO AN INTEGRATED CIRCUIT. HOWEVER AIR WITH A RELATIVE HUMIDITY HIGHER THAN 30‐35% SERVES AS A NATURAL CONDUCTOR THAT ALLOWS CHARGES TO LEAVE OBJECTS. MOLECULES OF WATER TOUCH THE OBJECT AND ABSORB THE CHARGE AND, IN TURN, COME INTO CONTACT WITH OTHER MOLECULES OF VAPOR, CAUSING THE EXCESS CHARGES TO SPREAD AWAY. EFFECT OF LOW HUMIDITY ON ELECTROSTATIC DISCHARGES (ESD)

24. EFFECT OF LOW HUMIDITY ON SEMICIRCULAR LIPOATROPHY (LS) THE SEMICIRCULAR LIPOATROPHY IS A BENIGN AND REVERSIBLE DISORDER OF THE SUBCUTANEOUS FAT THAT IS OFTEN MANIFESTED WITH A COLLAPSE IN THE ANTERIOR AND LATERAL THIGH SURFACE AND IN THE FOREARMS; USUALLY AFFECTING FEMALE OFFICE WORKERS, IT MAY BE PRESENT BOTH IN ONE EXTREMITY (UNILATERAL) OR BOTH (BILATERAL) AND CAN BE ACCOMPANIED BY ITCHING, CHANGES IN THE SENSITIVITY OF THE AREA AND, LESS FREQUENTLY, BY DISCOMFORT AND PAIN.Environmental risks Electronic  devices Conductive floor Conductive desks 95% of subjects are women Thighs and  forearms are the  most affected 72 cm: height of office  desks matching with the level of  affected areas THIS DISEASE APPEARED IN EPIDEMIC FORM IN FEBRUARY 2007 IN BARCELONA, AND SINCE THEN IN A GREATER NUMBER OF CASES IN DIFFERENT OFFICES IN THE COUNTRY. DESPITE STILL FAIRLY UNKNOWN, LS HAS TO DO WITH THE POSITION IN FRONT OF A DESK WITH UNGROUNDED METAL FRAMES, AND WITH A LOW RELATIVE HUMIDITY WHICH FAVORS ELECTROSTATIC DISCHARGES (ESD). IN OFFICES WHERE LS LESIONS HAVE BEEN IDENTIFIED MAGNETIC FIELDS WERE ALWAYS SIGNIFICANTLY HIGH AND THE RELATIVE HUMIDITY WAS BELOW 30%‐35%. IN ORDER TO PREVENT LS THE ENVIRONMENTAL RELATIVE HUMIDITY SHOULD NOT BE LOWER THAN 35% LS: depression on the thighs in  the form of semi‐circular band 

25. COMFORT IN OCCUPIED SPACES INDUSTRIAL ENVIRONMENTS OFFICES, SHOP MALLS, THEATERS 30%‐35% (1) AUTOMOTIVE PAINTING BOOTH 50%‐70% ± 2% HEALTH CARE FACILITIES CELLOFANE WRAPPING 45% CERAMIC FACTORIES  60% CRITICAL & INTENSIVE CARE 30% ELECTRICAL PRODUCTS  40% NEWBORNE NURSERY ROOMS     30% GUM  45% RECOVERY ROOMS 30% (2) LEATHER WORKINGS  40% OPERATING ROOMS 30% (3) LENS GRINDING 80% ART GALLERIES, MUSEUMS, LIBRARIES PAPER WORKING 45% PAINT 80% ART GALLERIES, MUSEUMS 40% PHOTO STUDIOS  40% LIBRARIES 40% PHOTOGRAPHIC MATERIAL FACILITIES  30% DATACOM FACILITIES PLYWOOD HOT PRESSING 60% PRINTING PLANTS  45% DATA CENTERS 30%‐35% (4) SEMICONDUCTORS FACTORIES   35%‐40% ± 2% TELECOMMUNICATION FACILITIES 20% TEXTILE PLANTS – KNITTING 45% CLEAN ROOMS ‐ LABORATORIES TOBACCO SOFTENING 85% TOBACCO CIGAR/CIGARETTE MAKING  55% CLEAN ROOMS 40%‐50% ± 5% WOOD WORKING  45% LABORATORIES 35%‐50% FOODSTUFF CONSERVATION HOTEL, MOTEL, DORMITORIES FRUITS 70%‐90% HOTEL, MOTEL 30% HAM ‐ SAUSAGES 75% DORMITORIES, JAILS 30% MEAT 70% ANIMAL AND CROP FARMS TEA 65% TOBACCO 65% ANIMALS 40‐50 40% VEGETABLES 90% ENVIRONMENTAL CONTROL FOR PLANTS 50% WINERIES >75%‐80% 1) ANSI/ASHRAE STANDARD 55‐2013 does not specify a minimum humidity level for thermal comfort. Non‐thermal comfort factors , such as skin drying, irritation  of mucus membranes, dryness of the eyes,  and static electricity generation, may place limits on the acceptability of very low humidity environments. 2) ANSI/ASHRAE/ASHE 170‐2013 suggests no lower limits: see above. 3) ANSI/ASHRAE/ASHE 170‐2013 suggests a limits of 20%; a higher value is advisable for older electronic equipment and for risk of gas explosion.due to sparks. 4) Lower values (i.e.: 20%) are allowable for servers rooms; a limit of 30% is recommended for personnel health reasons. RECOMMENDED MINIMUM RELATIVE HUMIDITY LIMITS

26. HUMIDIFICATION TECHNOLOGIES TYPE OF HUMIDIFIERS

27. ISOTHERMAL HUMIDIFIERS THE VAPOR GENERATION CAN BE OBTAINED BY PROVIDING EXTERNAL ENERGY THAT IS USED TO HEAT THE WATER TO BOILING TEMPERATURE AND THEN TO OBTAIN ITS CHANGE OF STATE. THE HOT STEAM PRODUCED IS DISPERSED IN THE AIR WHOSE TEMPERATURE IS RAISED TO A SMALL EXTENT; FOR THIS REASON THE PROCESS IS CALLED ISOTHERMAL. THE HUMIDIFIERS OF THIS TYPE ARE COMMONLY ENERGIZED WITH ELECTRICITY AND THEREFORE HAVE AN OPERATING COST WHICH OFTEN RESTRICTS THEIR APPLICATION TO LIMITED CAPACITIES. FOR HIGHER RATES ARE AVAILABLE EQUIPMENT BASED ON THE COMBUSTION OF METHANE OR LPG. ISOTHERMAL HUMIDIFIERS ARE FAIRLY SIMPLE TO INSTALL, ENSURE THE HYGIENIC PROPERTIES OF LIVE STEAM AND CAN BE USED BOTH FOR DIRECT DISTRIBUTION IN THE ROOM OR IN DUCTED AIR HANDLING UNITS. 0 5 10 15 20 25 30 35 40 25 20 15 10 5 0 DRY BULB TEMPERATURE ‐ °C ABS. HUMIDITY ‐gV/kgA VAPOR PARTIAL PRESSURE ‐KPA 1 2 3 0 0,5 2,5 1,5 3,5 1,82 21,2 11,3 4,3 0,72 Isothermal humidifcation of air to bring the absolute humidity from 4,3  g/kg (@ 20°C ‐ 30% RH) to 11,3  g/kg (introduction of 7 g/kg of dry air)

28. 1 Water fill valve 8 Cylinder full probe 2 Flow restrictor 9 Electrode leads 3 Filling pipe 10 Electrodes 4 Cylinder fill pipe 11 Steam cylinder 5 Overfill pipe 12 Bottom filter 6 Conductivity probe 13 Drain valve or pump 7 Fill cup IT IS A SIMPLE AND LOW PRICED TYPE OF EQUIPMENT IN WHICH TWO OR MORE METAL ELECTRODES CONNECTED TO ELECTRICAL MAINS USE WATER AS A RESISTIVE ELEMENT, HEATING IT UP TO BOILING POINT. THE CAPACITY CONTROL IS GOT BY VARYING THE DEPTH OF IMMERSION OF THE ELECTRODES BY MEANS OF THE FILLING AND WATER DRAINAGE SOLENOID VALVES. IMMERSED ELECTRODE HUMIDIFIERS SHOULD BE FED WITH NORMAL DRINKING WATER: THE ONLY REQUIRED MAINTENANCE IS CLEANING OR REPLACEMENT OF THE CYLINDER WHEN ELECTRODES ARE COVERED WITH LIME. THEY ARE AVAILABLE IN A RANGE FROM 1 TO 130 KG/H. IMMERSED ELECTRODE HUMIDIFIERS STEAM CYLINDER

29. 1 Antifoaming sensor 11 Drain tempering pipe 2 Overfill diaphragm 12 Drain tempering valve 3 Filling diaphragm 13 Filling valve 4 Filling tank 14 Drain pump 5 Conductivity probe 15 Antiadhesive film 6 Equalizer pipe 16 Overtemperature PTC 7 Fill cup 17 Heaters 8 Filling pipe 18 Water temp. sensor 9 Level sensor 19 Thermal insulation 10 Overflow pipe WITH THE ABILITY TO ELECTRONICALLY MODULATE THE POWER OF THE HEATERS BY MEANS OF SOLID STATE RELAYS, ADVANCED DEVICES ALLOW VERY HIGH LEVELS OF ACCURACY (± 1%) IN CONTROLLED HUMIDITY. THEY CAN OPERATE WITH NORMAL TAP DRINKING WATER HOWEVER THE USE OF DEMINERALIZED WATER REDUCES MAINTENANCE VIRTUALLY TO ZERO. THE POWER RANGE ARRIVES UP TO 80 KG/H. IMMERSED HEATER HUMIDIFIERS THESE DEVICES INCLUDE RESISTIVE ELEMENTS WHICH ARE SUPPLIED WITH ELECTRICITY TO BOIL THE WATER THAT IS MAINTAINED AT A CONSTANT LEVEL IN A TANK. HEATING  ELEMENT

30. 1 Water on‐off tap 13 Gas line 2 Filling valve 14 Gas on‐off tap 3 Antifoaming sensor 15 Gas burner(s) 4 Steam outlets 16 Drain valve 5 Boiler 17 Filter 6 Flue gas 18 Drain pump 7 Electrical panel 19 Drain network 8 Gas temp. sensor 20 Conductivity meter 9 Level sensor 21 Drain pipe 10 Preheat sensor 22 Water line 11 Heat exchanger(s) 23 Safety thermostat 12 Air inlet 24 Bottom drain pipe THE PRINCIPLE OF OPERATION OF THESE DEVICES, IN WHICH NATURAL GAS OR LPG ARE BURNED INSIDE OF A STAINLESS STEEL HEAT EXCHANGER IMMERSED IN THE WATER, IS SIMILAR TO THAT OF THE ELECTRICAL HEATER ONES; STEAM PRODUCTION IS FINELY MODULATED BY ADJUSTING THE GAS SUPPLY. THE MAIN ADVANTAGE STANDS IN THE LOWER COST OF ENERGY SOURCE COMPARED WITH ELECTRICITY. THEY CAN OPERATE BOILING DRINKABLE MAINS WATER OR DEMINERALISED WATER, IN THIS CASE DRASTICALLY REDUCING REGULAR MAINTENANCE. THE AVAILABLE RANGE CAN REACH UP TO 360 KG/H. GAS FIRED HUMIDIFIERS HEAT  EXCHANGER

31. ADIABATIC HUMIDIFIERS ALTERNATIVELY, THE EVAPORATION CAN TAKE PLACE IN ADIABATIC MODE, i.e. WITHOUT THE NEED OF EXTERNAL ENERGY. THE HEAT REQUIRED FOR THE EVAPORATION IS SUPPLIED FROM THE AIR THAT IS BEING HUMIDIFIED, SO THAT IT GETS COLDER FOLLOWING AN ISENTALPIC LINE LIKE THE BLUE ONE IN THE PSYCROMETRIC DIAGRAM. FOR THIS REASON, IN ORDER TO MAINTAIN THE FINAL TEMPERATURE AT THE DESIRED VALUE, IT IS OFTEN NECESSARY A PREHEAT PROCESS (RED LINE). ADIABATIC HUMIDIFIERS PROVIDE A WIDE AREA OF   INTERFACE BETWEEN THE AIR AND THE LIQUID WATER, WHICH EVAPORATES SPONTANEOUSLY. THE MAIN ADVANTAGE OF THE ADIABATIC HUMIDIFICATION STANDS IN THE ENERGY CONSUMPTION: THE ONLY POWER REQUIRED BY THE EQUIPMENT IS THAT FOR ATOMIZING OR RECIRCULATING THE WATER ACCORDING TO THE TECHNOLOGY USED. 0 5 10 15 20 25 30 35 40 25 20 15 10 5 0 DRY BULB TEMPERATURE ‐ °C ABS. HUMIDITY ‐gV/kgA VAPOR PARTIAL PRESSURE ‐KPA 1 2 3 0 0,5 2,5 1,5 3,5 1,82 38,1 11,3 4,3 0,72 PREHEAT PROCESS                ADIABATIC HUMIDIFICATION Adiabatic humidifcation of air to bring the absolute humidity from 4,3  g/kg (@ 20°C ‐ 30% RH) to 11,3  g/kg (introduction of 7 g/kg of dry air)

32. IN THIS KIND OF ADIABATIC HUMIDIFIERS THE AIR IS PASSED THROUGH MODULAR PADS, I.E.: HONEYCOMB STRUCTURES OF RESIN‐IMPREGNATED CELLULOSE OR GLASS FIBER OFFERING A WIDE INTERFACE AREA. THE PADS, PLACED VERTICALLY, ARE KEPT WET BY A WATER FLOW DRAWN FROM A BOTTOM TANK BY A PUMP AND DISTRIBUTED ON THEIR UPPER EDGE. WET MEDIA HUMIDIFIERS ONLY PART OF THE WATER DISTRIBUTED ONTO THE PADS EVAPORATES WHEN THE REST IS RECIRCULATED; THE EVAPORATION PROCESS INCREASES THE CONCENTRATION OF SALTS WHICH MAY BUILD UP ON THE SURFACE, FORCING TO CLEAN OR REPLACE THE PADS WHEN CLOGGED; FURTHERMORE THEY SHOULD BE PERIODICALLY CONTROLLED BECAUSE THE PRESENCE OF A WARM WATER RECIRCULATION POTENTIALLY PROMOTES A RISKY BACTERIAL GROWTH. LAST BUT NOT LEAST, THE AIR SIDE PRESSURE DROP OF THE PADS REQUIRES AN ADDITIONAL ENERGY CONSUMPTION EVEN WHEN NO HUMIDIFICATION IS REQUIRED. THEIR USE, WIDESPREAD FOR THE LIMITED PRICE, SHOULD BE CAREFULLY EVALUATED LOOKING ALSO AT THE OPERATING COSTS.

33. HIGH PRESSURE ATOMISING SYSTEMS THESE DEVICES ARE EQUIPPED WITH A VOLUMETRIC PUMP WHICH PRESSURIZES THE WATER TO VALUES BETWEEN 70 AND 100 BAR AND DELIVERS IT TO SMALL NOZZLES THAT PRODUCE A FINE MIST (DROPLETS OF 10‐15 MICRON) EASILY ABSORBED BY AIR STREAM(*). (*) the surface offered by 1 liter of water atomized at 15 micron is as high as 400 square meters THE DISTRIBUTION PIPING NETWORK THAT SUPPORTS AND SUPPLIES THE NOZZLES IS POSITIONED IN AN AIR DUCT OR PLACED DIRECTLY INTO THE ENVIRONMENT TO HUMIDIFY. THESE DEVICES MAY REACH AN EXCELLENT LEVEL OF ACCURACY (± 2%) OF THE HUMIDITY IN THE CONTROLLED SPACE AND VERY HIGH CAPACITIES WITH A NEGLIGIBLE ELECTRIC CONSUMPTION ABSORBED BY THE PUMP (<4 W PER LITER OF SPRAYED WATER). THEY ARE HYGIENICALLY SAFE WITH NO BACTERIAL GROWTH BECAUSE THE QUANTITY OF NON ABSORBED WATER ‐ USUALLY VERY SMALL, IF ANY ‐ IS DRAINED OFF. THE USE OF DEMINERALISED OR SWEETENED WATER IS RECOMMENDED TO PREVENT CLOGGING OF THE NOZZLES. THESE ATOMISING SYSTEMS MAY REACH A CAPACITY OF MANY THOUSANDS OF KG/H PUMPING STATION ATOMIZING NOZZLE NOZZLE RACK NOZZLE RACK IN AHU SECTION SUSPENDED TYPE

34. 1 Air filter 9 Float level sensor 2 Rear fans 10 Tank 3 Atomised water 11 Driver 4 Diffuser 12 Piezo transducer 5 Atomisation chamber 13 Power supply 6 Fill valve 14 Front fans 7 Overflow pipe 15 Laminar air flow 8 Drain valvce ULTRASONIC HUMIDIFIERS PROVIDE AN EXTRA FINE ATOMIZATION OF WATER (≈ 3 μm) BY MEANS OF THE HIGH‐ FREQUENCY VIBRATION (CLOSE TO 1,7 MHZ) OF A PIEZOELECTRIC ELEMENT OR MORE, IN PARALLEL. N.B.:  the surface offered by 1 liter of water atomized at 3 micron is 2000 square meters BEST ULTRASONIC HUMIDIFIERS REACH EXCEPTIONAL LEVELS OF PRECISION (± 1%) IN THE ENTIRE RANGE OF THEIR RATED CAPACITY AND, THANKS TO THE HIGH EFFICIENCY OF ABSORPTION, THEY ARE SUITABLE FOR THE DISTRIBUTION OF THE PRODUCED MIST DIRECTLY INTO THE ROOM AS WELL AS IN DUCTED SYSTEMS. DUE TO SIZE AND COST THEY ARE CONVENIENT FOR SMALL AND MEDIUM INSTALLATIONS (0,5 TO 15 kg/h). FOR ULTRASONIC HUMIDIFIERS THE USE OF DEMINERALISED WATER IS HIGHLY RECOMMENDED. ULTRASONIC HUMIDIFIERS STAND ALONE UNIT SMALL SIZE UNITDUCTED TYPE UNIT

35. VAPOR PRODUCTION < 2 kg/h 2‐20 kg/h 20‐100 kg/h > 100 kg/h ISOTHERMAL  HUMIDIFIERS IMMERSED ELECTRODES HIGH ELECTRICAL  ENERGY INPUT IMMERSED HEATERS HIGH ELECTRICAL  ENERGY INPUT GAS FIRED TOO SMALL ADIABATIC  HUMIDIFIERS HIGH PRESSURE ATOMISERS TOO SMALL ULTRASONIC TOO LARGE TOO LARGE WET MEDIA TOO SMALL TOO SMALL HYGIENIC  PROPERTIES DISTRIBUTION SYSTEM DIRECT IN ROOM DUCTED ISOTHERMAL  HUMIDIFIERS IMMERSED ELECTRODES IMMERSED HEATERS GAS FIRED ADIABATIC  HUMIDIFIERS HIGH PRESSURE ATOMISERS WITH NO  RECIRCULATION WITH DISTRIBUTED  TERMINALS ULTRASONIC IF EQUIPPED WITH  AUTOMATIC DRAINAGE WET MEDIA REGULAR INSPECTION  REQUIRED NOT PRACTICAL GENERAL SUITABILITY TABLE

36. MANY THANKS FOR  YOUR ATTENTION luigi.nalini@carel.com

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