1、 AEROSPACE INFORMATION REPORT (R) Aircraft Humidification Issued 1982-04 Revised 2005-03 Superseding AIR1609 AIR1609 REV.A TABLE OF CONTENTS 1. SCOPE 3 1.1 Purpose3 2. REFERENCES.3 2.1 Applicable Documents .3 2.1.1 SAE Publications3 2.1.2 Government Publications.3 2.2 Other Publications4 2.3 Nomencl
2、ature.4 2.4 Units.5 3. GENERAL BACKGROUND .5 4. PHYSIOLOGICAL EFFECTS OF LOW HUMIDITY .5 4.1 Performance.6 4.2 Respiratory Effects.6 4.3 Effective Temperature7 4.4 Exposure Time.7 5. HUMIDITY LEVELS IN PRESSURIZED AIRCRAFT .7 5.1 Measurement of Cabin Humidity8 Reaffirmed 2010-05SAE Technical Standar
3、ds Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole respo
4、nsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2010 SAE International All rights reserved. No part of this publication may be reproduced, store
5、d in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Emai
6、l: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedbackon this Technical Report, please visit http:/www.sae.org/technical/standards/AIR1609ACopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking per
7、mitted without license from IHS-,-,-SAE AIR1609 Revision A - 2 - 6. HUMIDIFICATION IN AIRCRAFT AT HIGH ALTITUDE 10 6.1 Humidifier Input Requirements.11 6.2 Methods of Humidification13 6.3 Humidification Problems 15 6.4 Water System Interfaces17 7. PENALTIES OF HUMIDIFICATION.18 7.1 Weight18 7.2 Main
8、tenance.18 7.3 Operation .18 8. WATER TREATMENT .19 8.1 Health Requirements .19 8.2 Dissolved Solids.199. NOTES.20 FIGURE 1 Moisture Loss from the Average Human9 FIGURE 2 Water Requirements for Humidification12 Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reprod
9、uction or networking permitted without license from IHS-,-,-SAE AIR1609 Revision A - 3 - 1. SCOPE: This SAE Aerospace Information Report (AIR) covers the design parameters for various methods of humidification applicable to aircraft, the physiological aspects of low humidities, the possible benefits
10、 of controlling cabin humidity, the penalties associated with humidification, and the problems which must be solved for practical aircraft humidification systems. The design information is applicable to commercial and military aircraft. The physiological aspects cover all aircraft environmental cont
11、rol applications. 1.1 Purpose: The purpose of this AIR is to provide guidelines for the design of aircraft humidification systems. Physiological effects of humidity levels on crew and passengers are reviewed.Various techniques used for cabin humidification are discussed and evaluated. Various techni
12、cal issues are addressed, and effects associated with humidification systems are described.2. REFERENCES: 2.1 Applicable Documents: The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other
13、publications shall be the issue in effect on the date of purchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific
14、 exemption has been obtained. 2.1.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.2.1.1.1 ARP987 The Control of Excess Humidity in Avionics Cooling 2.1.1.2 AIR1204 Control of Water Carryover from the Environmental Control System and Condensation on the Struc
15、ture 2.1.1.3 AIR1168/3 Aerospace Applied Thermodynamics Manual, Section 3, Aerothermodynamic Systems Engineering and Design 2.1.2 Government Publications: Available from Superintendent of Documents, P.O. Box 371954, Pittsburgh, PA 15250-7954. 2.1.2.1 Food and Drug Administration Public Health Servic
16、e Publication No. 308, Handbook on Sanitation of Airlines Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1609 Revision A - 4 - 2.2 Other Publications: 2.2.1 D. A. McIntyre; Indoor Climate, Ap
17、plied Science, 1980. 2.2.2 L. B. Anderson MD, Gunnar R. Lundquist MSC, Preben L. Jensen, Donald F. Proctor MD; Human Response to 78 Hour Exposure to Dry Air, Arch. Environmental Health, Vol. 29, December, 1974. 2.2.3 ASHRAE Handbook, Fundamentals Volume, 1997. 2.2.4 W. F. Storm, et al; Effect of Low
18、 Humidity on Human Performance, USAF School of Aerospace Medicine, Brooks AFB, Texas. SAM-TR-73-3, Feb 1973. 2.2.5 J. R. Dille MD; Further Information Concerning Humidity Control for Air Crew Performance. FAA-CAMI Oklahoma City, OK. File AC-100 Oct 1970. 2.2.6 E. W. Dunklin and T. T. Puck; The Letha
19、l Effect of Relative Humidity on Airborne Bacteria. Journal of Experimental Medicine 87:87, Feb 1948. 2.2.7 W. H. Carrier: Rational Psychrometric Formulae, Transactions A.S.M.E., 1911. 2.3 Nomenclature: This list contains symbols used in equations, charts and descriptions in this AIR. G Water added
20、to increase humidity, kg/min (lb/min) mpAverage moisture generated per passenger, kg/min (lb/min) mcAverage moisture generated per crew member, kg/min (lb/min) npNumber of passengers ncNumber of crew members PcCabin pressure, kPa absolute (psia) PvSaturated vapor pressure of water at the dry bulb te
21、mperature, kPa absolute (psia)RH Relative humidity, % WaOutside air flow rate into the cabin, kg/s (lb/min) WrRecirculated air, kg/s (lb/min) Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR16
22、09 Revision A - 5 - 2.3 (Continued): x Ratio of moisture in recirculated air to moisture in cabin air aSpecific humidity, ambient, kg/kg (lb/lb) of dry air cSpecific humidity, cabin, kg/kg (lb/lb) of dry air sWater vapor at saturation at dry bulb temperature and at the cabin pressure, kg/kg (lb/lb)
23、of dry air gr Grain = 0.0000648 kg (7000 gr = 1 lb) 2.4 Units: All equations in this AIR may be used with metric (SI) or English units if consistency is maintained.3. GENERAL BACKGROUND: World wide variations in relative humidity range from as little as 6% in desert areas to 100% when rain is fallin
24、g or the temperature is equal to or just below the dew point. The absolute (specific) humidity or water content shows an equally wide variation, being less than 2 g of water per kg of dry air (14 gr/lb) in cold winter climates to as high as 29 g/kg (200 gr/lb) during summer months in tropical areas.
25、 The majority of people who are airline passengers live in areas where the relative humidity is between 30 to 60% most of the time. Exposure to a combination of high temperature and humidity causes almost immediate discomfort. The effect of exposure to very low levels of humidity takes considerably
26、longer to be noticeable. Flight and cabin crews of long-range aircraft, having frequent extended-duration exposures, are among the most susceptible to the effects of low humidity, as typically aircraft humidity in cruise is often substantially lower than 30%. This is the consequence of flying at alt
27、itudes where the ambient air contains no or very little humidity. Ambient air is compressed and used to provide air conditioning inflow to the cabin.) 4. PHYSIOLOGICAL EFFECTS OF LOW HUMIDITY: Ambient temperature and humidity affect the temperature and water balance of the human body. The inspired a
28、ir is brought to body temperature and a saturated level prior to reaching the lungs by extracting heat and water from the mucosa lining the upper respiratory tract.This process cools and dries the surface mucosa. During expiration, both heat and water are recovered from the alveolar air, 37 C (98 F)
29、 and 100% RH as it contacts the colder mucosa of the nasopharynx. This net transfer of heat and moisture is dependent on ambient humidity and temperature. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-
30、,-,-SAE AIR1609 Revision A - 6 - 4. (Continued): The physiological effects of low humidity, as can be found in aircraft cabins during cruise, are unclear. There are numerous reported instances of airline passengers and crew complaining of dry noses and throats, and “gritty“ eyes. The sensation of dr
31、yness of the nose is attributed to drying out of the mucosa. Most of the evidence of discomfort related to low humidity is difficult to evaluate (reference D. A. McIntyre; Indoor Climate, Applied Science, 1980). Some investigations, under carefully controlled conditions, have concluded that there is
32、 no physiological need for humidification of air (references: L. B. Anderson MD, Gunnar R. Lundquist MSC, Preben L. Jensen, Donald F. Proctor MD; Human Response to 78 Hour Exposure to Dry Air, Arch. Environmental Health, Vol. 29, December, 1974 and ASHRAE Handbook, Fundamentals Volume). It should be
33、 noted that in cold climates, the relative humidity inside buildings can be quite low. For example, if the outside air is saturated at -6.7 C (20 F), the RH at 23.9 C (75 F) is only 11%. Many people are exposed to such humidity levels for long durations, apparently without significant adverse effect
34、s or discomfort. 4.1 Performance: No adverse effect of low humidity on performance has been established. USAF School of Aerospace Medicine experiments showed that environments of 0.5 mm Hg (66.5 Pa) vapor pressure and/or simulated 2.44 km (8000 ft) barometric pressure (with a moisture content of abo
35、ut 0.6 g/kg (4 gr/lb) had no adverse effects on performance during four36-hour chamber exposures (reference W. F. Storm, et al; Effect of Low Humidity on Human Performance, USAF School of Aerospace Medicine, Brooks AFB, Texas. SAM-TR-73-3, Feb 1973). Department of Transportation Federal Aviation Adm
36、inistration investigations have been conducted to evaluate any performance effects of low humidity.These studies concluded that the information presented with regard to humidity effects did not show that low humidity had safety implications (reference J. R. Dille MD; Further Information Concerning H
37、umidity Control for Air Crew Performance. FAA-CAMI Oklahoma City, OK. File AC-100 Oct 1970). 4.2 Respiratory Effects: Many medical practitioners believe that low winter humidities predispose individuals towards infection and have recommended humidification for those who suffer from respiratory troub
38、les. The dispersal of bacterial is affected by humidity, in that bacteria are carried on small dust particles (reference W. H. Carrier: Rational Psychrometric Formulae, Transactions A.S.M.E., 1911). Increasing relative humidity encourages the particles to agglomerate, which will increase the rate at
39、 which they settle out of the atmosphere. Humidification systems may, therefore, be desirable in military airplanes used as mobile hospitals. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR16
40、09 Revision A - 7 - 4.2 (Continued): Some epidemiological investigations have been made which point to low atmospheric humidities as a factor in increasing the incidence of infection. Although these investigations support each other, none can really be considered conclusive (reference D. A. McIntyre
41、; Indoor Climate, Applied Science, 1980). 4.3 Effective Temperature: The effective temperature (ET*) is an index that combines into a single value the effects of dry-bulb temperature, relative humidity and air velocity on the sensation of comfort (reference ASHRAE Handbook, Fundamentals Volume, 1997
42、). It is similar to the older effective temperature (ET) used earlier by the American Society of Heating Refrigeration and Air Conditioning Engineers, but it is based upon more current tests on effects of environment on human comfort. The index shows that as humidity is decreased, dry bulb temperatu
43、re must be increased to achieve the same sensation of warmth. 4.4 Exposure Time: Any effects of low humidity are not immediate. The incidence of passenger complaints tends to be associated with flights of 3 to 4 hours or longer, increasing with flight time. Crew discomfort is more prevalent due to t
44、heir more frequent exposure to low humidity conditions. Military crews on flights lasting up to approximately 24 hours have experienced discomfort due to low humidities. Commercial flights can last up to approximately 14 hours on intercontinental routes, so commercial flight crews may experience sim
45、ilar effects. Frequent intake of water may reduce this discomfort. 5. HUMIDITY LEVELS IN PRESSURIZED AIRCRAFT: The cabin and flight station humidity is a function of the ambient humidity, ventilation rate, moisture generated in the cabin and the temperature of the cabin or flight station. The specif
46、ic humidity of air in the cabin can be calculated using the general Equation 1 given below. The recirculation factor (x) is included to cover systems where recirculated air may be treated by passing through charcoal or other chemical filters, which may remove some of the moisture. Where air recircul
47、ation is not used or where air recirculation is used without moisture removal, the denominator in Equation 1 becomes Wa.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1609 Revision A - 8 - 5.
48、 (Continued): The rate of moisture generation by passengers and crewmembers depends upon the cabin temperature, and can be determined from Figure 1. The moisture generated in galleys has not been included since it is generated intermittently and usually is vented overboard. )x1(WWmnmnWraccppaac+= (E
49、q.1) Nomenclature for this equation is found in 2.3. Note that Equation 1 assumes that no moisture is being added or removed by humidification or dehumidification systems, Equation 1 also assumes that no moisture is being removed by the air conditioning system or condensing on cold surfaces within the cabin (with the exception of moisture removal from reci
