ASHRAE JOURN 38-7 TDS-1996 ASHRAE Journal《ASHRAE日报第38卷第7号 1996年7月》.pdf

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1、 110 T54 1111 Heres news thats bound to (Circle No 2 on Reader Service Card) be the talk of the industry. The MetasyP Fac $79 (includes postage for Canadian). $149 international (includes air mail). Member- ship subscriptions have a common June expiration. Non- membersubscriptions mayvar. Payment (U

2、S funds) required with all orders. POSTMASTER: Send form 3579 to: ASHRAE Journal, 1791 Tuliie Circle N.E., Atlanta, GA 30329 LETTERS/MANUSCRIPTS-Letters to the editor and manu- scripts for publication should be sent to: William R. Coker, Editor, ASHAEJournal, i791 Tullie Circle N.E., Atlanta, GA 303

3、29 MICROFILM-This publications microfilmed by University Microfilms, inc.(UMI), 300 North Zeeb Road, Ann Arbor, MI 481 06. For information on cost and issues available, you may contact UM1 at 313-761-4700. ASHRAE Journal July 1996 4 ASHRAE TITLESJOURN 3-?*TDS 96 0759650 0524115 536 W With a natural

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8、e (Circle No. 6 on Reader Service Card) - _ ASHRAE TITLE*JOURN 3-7rTDS 9b 0759650 0524336 472 11 T 6 ASHRAE“ JOURNAL 1791 Tullie Circle N.E. Atlanta, Georgia 30329-2305 ASHRAE Home Page http:/www.ashrae.org 404-636-8400 FAX 404-321 -5478 Controlling the Environment Through Knowledge EXECUTIVE VICE P

9、RESIDENTFUBLISHER Frank M. Coda PUBLISHING DIRECTOR W. Stephen Comstock EDITORIAL EDITOR William R. Coker e-mail bcokerashrae.org MANAGING EDITOR Fred Turner e-mail fturnerashrae.org ASSOCIATE EDITOR Shannon E. Powers-Jones e-mail spowersashrae.org WASHINGTON BUREAU J.E. Cox, P.E., Ph.D. Charles R.

10、Mir e-mail washofcashrae.org PUBLISHING SERVICES PUBLISHING SERVICES MANAGER Scott A. Zeh GRAPHICS Susan Boughadou TYPOGRAPHY Kellie M. Frady Stefan R. Moore Nancy F. Thysell CIRCULATION CIRCULATION MANAGER Phyllis Maurer ADVERTISING ASSOCIATE PUBLISHER Edwin F. Farley ADVERTISING PRODUCTION MANAGER

11、 Irene F. Eggeling PRESIDENT Richard B. Hayter, P.E., Ph.D. James E. Hill, Ph.D. TREASURER Donald E. Holte, P.Eng. VICE PRESIDENTS Harley W. Goodman, Jr., P.E. George A. Jackins, P.E. Laurance S. Staples, Jr. James E. Wolf SECRETARY Frank M. Coda ASHRAE OFFICERS PRESIDENT-ELECT ,POLICY GROUP 1995-96

12、 Chairman JournalAnsights Committee Charles H. Culp. 111, Ph.D. 5 Member of The Audit Bureau of Circulation Commentary Economics, Perceptions and Technical Reality conomics, their perception and technical reality are interwo- E ven in HVAC design. The articles in this issue revolve around William R.

13、 Coker - these factors. Richard A. Evans and Dr. Robert J. Tsal examine the economics and performance of duct systems that include discussions on duct shapes from round and flat to oval; what fittings should be used and those to avoid; when and how to seal leakage; where oversizing is appropriate; w

14、hen computer analysis can use airflow modeling to sim- ulate the duct design; and where the computer will benefit the design and practical operation of the system. Practical operating experiences with commercial ground-source heat pumps have enabled R.L. Douglas Cane, S. Blair Clemes and Andrew Moms

15、on to share their study results of 12 commercial sites of ground-source heat pumps (GSHP). This report on an ASHRAE research project provides basic information that will be valu- able to engineers considering GSHP systems for their clients. The authors offer infor- mation including descriptions of t

16、he buildings and their systems, power costs, system performances, operating difficulties, and owner satisfaction. The focus remains on heat pumps in the following article and provides a comparison with radiant heating as examined by Richard D. Watson and Kirby S. Chapman. They look at the results of

17、 their study comparing electric radiant panel heating with conven- tional electric air heat pump and baseboard heating. The article uses performance pro- files for comparison with related output provided by the Building Comfort Analysis Program (BCAP). This program is a system layout and sizing desi

18、gn tool that predicts thermal comfort distribution and room air temperature in a radiantly or convectively heated or cooled building. The results of this study suggest that comparable levels of thermal comfort were provided by radiant and heat pump systems, but the radiant panels demonstrated a proj

19、ected 33% savings in comparison to the heat pump. Saving energy costs is the hallmark of an ASHRAE Technology Award. Taylor B. Bodkins thermal cool storage design and the WAC systems employed at the Shell Point Village retirement community is a Technology Award Case Study. The 12-month savings for t

20、he project was $48,356 and the payback two years. This modernization and retrofitting of an existing facility called for energy-efficient improvements within three multistory apartment buildings with 200 units totaling 48,546 fi (4 150 m2) Steve Taylor continues with a look at economics and adds per

21、ceptions and technical reality with his article, Series Fan-Powered Boxes: Their Impact on Indoor Air Quality and Comfort. Taylor examines the growing perception among HVAC designers that using series fan-powered boxes to increase the air supply to interior spaces has a positive benefit on comfort a

22、nd indoor air quality. Taylor does not believe that this contention is supported by research studies. While the benefits of series fan-powered boxes are ques- tionable, there is no question that the use of these devices in interior zones increases first costs, maintenance costs, noise levels and ene

23、rgy costs. This suggests that perhaps designers should investigate alternatives. rn William R. oker Journal Editor ASHRAE Home Page Update http:/www.ashrae.org Establishment of a new student section. This includes information about opportunities available in the HVAC 21% drop in amperage draw; 30% d

24、ecrease in supply air temperature; 13% drop in suction pressure.II The Queens Medical Center, Bullhead Cornmuniv Hospital, Az With Injuries Up 69% in 95 COLUMBUS, Ohio-A report released recently by the National Board of Boiler and Pressure Vessel Inspectors shows that accidents with injuries involvi

25、ng boilers and pressure vessels increased 69% in 1995, from 45 to 76. Accidents with deaths increased 63%, from 8 to 13. Albert J. Justin, the organizations executive director, said most of the in- crease in accidents with injuries involve unfired pressure vessels. These accidents, which accounted f

26、or 65 of the 76 accidents with injuries, in- creased from 19 to 65. Six of the 13 fatal accidents involved unfired pressure ves- sels. Operator error or poor maintenance was blamed in 52 of these accidents and five of the fatalities. In all, there were 2,612 accidents in- volving boilers and pressur

27、e vessels in 1995, a five percent increase over 1994. The largest number of accidents (1,234) involved steam heating boilers, fol- lowed by water heating boilers (597), power boilers (527), and unfired pres- sure vessels (245). The leading cause of accidents was low water conditions (1,330). Justin

28、said low water has been blamed for 4,800 ac- cidents since 1992. Other causes of 1995 accidents included operator error or poor maintenance (758), safety valves (40), limit controls (68), improp- er installation (55), improper repair (90), faulty design or fabrication (loo), and burner failure (161)

29、. Justin said the report shows the need for training and education to counteract human error and poor maintenance. “Only though a conscientious and concerted effort to keep owners and op- erators continually aware of the dangers associated with this equipment can we hope to effectively reduce the nu

30、mbcr of accidents and deaths,” he said. The National Board of Boiler and Pressure Vessel Inspectors is a not-for- profit corporation created in 1919 to promote safety and uniformity in con- struction, installation and repair. GUARANTEED SAVIIUGS I I Residential/Commer, conducted at the Adaptable Fir

31、e-Safe Demonstration house (AFSD), documented the en- ergy requirements and thermal comfort capabilities of three different heating systems: (1) heat pump with backup elec- trical strip; (2) electrical baseboard; and (3) electric fast-act- ing surface-mounted radiant ceiling panels. Outside temperat

32、ure, the indoor multilevel ambient air, mean radiant, and operative room temperatures, and electrical consump- tion were recorded by an 18-station data acquisition system every minute during the winter of 1993-94. The AFSD house, located in Bowie, Md., is a two-story 2,200 ft2 (204 m2) house with ei

33、ght-foot ceilings. The house was insulated to R-11 in the walls and floor and R-19 in the ceiling. Thermal Comfort, Mean Radiant, and Operative Tem- perature ASHRAE Standard 554 defines thermal comfort as the state of mind that expresses satisfaction with the thermal ewiron- ment. Occupant thermal c

34、omfort is an essential condition of any heating system5 If the window-to-wall area ratio in a room is large, the non-uniform thermal radiation field plays a significant and, in some cases, a primary role in creating a thermally com- fortable environment. 24 ASHRAE Journal July 1996 ASHRAE TITLEXcJOU

35、RN 38-7xTDS 96 0759650 052Y33.5 324 Figure 1 shows the top view of a room with a large window. The outdoor air temperature is 0F (-17.7“C) while the indoor temperature is 68F (20C). These conditions lead to an inside window surface temperature of 48F (9“C), assuming a window R-value of two. The pers

36、on standing near the window senses thermal discomfort due to: (1) a net radiative heat transmission through the window; and (2) a net radiative heat loss to the cool window surface. The first loss depends on the window transmissivity. Gener- ally, window glass is transparent below 1=4 pm and opaque

37、above 1=5pm. At nominal indoor surface temperatures of 75F (233C) about 2% of the radiation is transmitted through the window . The remaining 98% is either reflected back into the room or absorbed by the window. The second loss is due to radiation absorption by the rela- tively cool window surface.

38、Radiation that is incident on the window surface is partially absorbed, and then conducted to the outdoors through the window. Since the radiant emission di- rected from the cooler window towards the person is less than the emission directed from the person towards the window, the person experiences

39、 a net radiative heat loss. This net loss leads to a thermally uncomfortable cold feeling, even though the surrounding room air temperature is 68F (20C). The occupant could be made to feel thermally comfort- able by offsetting the net radiant heat loss to the environment with a corresponding heat ga

40、in from a radiant heater. This understanding suggests that air temperature alone is not a good measure of thermal comfort. Instead, the room air tem- perature and the radiant field play an integral part in establishing a level of thermal comfort. The consensus of human thermal comfort studie,- is th

41、at human thermal comfort is a function of: (1) air temperature, 6 Figure 1: The effect of a window in thermal cornfort sensations in a radiantly heated indoor environment. averaging the air and mean radiant temperatures results in an operative temperature within 1% of the true operative temperature

42、for most built environments. The NAHB Case Study The principles of heat transfer support the energy savings notential at eauivalent levels of ther- (2) mean radiant temperature, (3) ait veloc- ity, (4) relative humidity, (5) clothing, and (6) activity level. The mean radiant temper- ature is defined

43、 as the uniform temperature of an imaginary enclosure in which the ra- diationfrom the occupant equuls the radi- ant heat transfer in the actual nonunform enclosure. Of these six parameters, activity level and clothing requirements are predefined according to the type of built environment. For examp

44、le, the design of an office envi- ronment assumes the activity level is close to sedentary, and that people are attired with appropriate, predefined clothing. Addition- ally, the au. velocity is maintained low enough to prevent (2) room zoning; (3) quick recovery from setback; and (4) re- duced air

45、temperature. Quantifying the acceptable air temperature reduction or energy savings with a certain type of heating system, however, is only rele- vant to the individuals selecting a heat- ing system for their home. People demand thermal comfort for the lowest reasonable cost. The NAHB case study lit

46、erature search provides a ba- sis for energy and thermal comfort Performance claims used in field tests of radiant and conventional heating systems. The NAHB literature review found that much of the discus- the field, Consequently, the expected energy savings in a home can not accurately be predicte

47、d with available documented in- formation. Uncertainty exists regarding (1) local thermal comfort conditions; (2) the exact relationship between the air and mean radiant temperatures leading to the operative temperature; and (3) the dynamics of thermal comfort and energy performance for various heat

48、ing systems under tran- sient as compared to steady-state conditions. Field testing of two heating systems within the same stmc- ture eliminates many of the variables involved with other is a function of the quentlY, the remaining parmeters, le “ te*rlpelahire and sion in the literature is based on

49、insufficient evidence from ASHRAE Journal July 1996 25 ASHRAE TITLE*JOURN 38-7*TDS 96 0759650 0524336 260 SS forms of testing. Energy performance data, thermal comfort conditions as ex- perienced by actual occupants, and op- erative temperatures as recorded by sensors provide an analytical perspec- tive of the heating systems. Issues ex- amined in the case study included : 1. The conditions under which 6“ to 8F (-14.4 to -13.3“C) air tempera- ture setbacks are obtainable. 2. Sustained thermal comfort wh