BS 4856-3-1975 Methods for testing and rating fan coil units unit heaters and unit coolers - Thermal and volumetric performance for heating and cooling duties with additional ducti.pdf

1、BRITISH STANDARD BS 4856-3: 1975 Methods for Testing and rating fan coil units, unit heaters and unit coolers Part 3: Thermal and volumetric performance for heating and cooling duties; with additional ducting UDC 697.971.001.42 + 697.356.001.42BS4856-3:1975 This British Standard, having been approve

2、d by the Refrigeration, Heating and AirConditioning Industry Standards Committee, was published under the authorityofthe Executive Boardon 30September1975 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference RHE/6 Draft for comment 73/34432DC ISBN 0 580 0

3、8615 1 Co-operating organizations The Refrigeration, Heating and Air Conditioning Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Association o

4、f Consulting Engineers* Association of Manufacturers of Domestic Electrical Appliances Boiler and Radiator Manufacturers Association* British Gas Corporation British Mechanical Engineering Confederation British Oil and Gas Firing Equipment Manufacturers Association British Refrigeration and Air Cond

5、itioning Association* Department of the Environment Department of Health and Social Security* Electricity Supply Industry in England and Wales Engineering Equipment Users Association Heating and Ventilating Contractors Association* Heating and Ventilating Research Association * HEVAC Association* In

6、stitute of Fuel Institution of Gas Engineers Institution of Heating and Ventilating Engineers* Institute of Refrigeration* Lloyds Register of Shipping Manufacturers Association of Radiators and Convectors* Ministry of Defence* National Coal Board Society of British Gas Industries Water-tube Boilerma

7、kers Association The organizations marked with an asterisk in the above list, together with the following, were directly represented on the Committee entrusted with the preparation of this British Standard: Department of the Environment, Building Research Establishment Greater London Council Unit He

8、ater Manufacturers Association Oil Companies Materials Association Amendments issued since publication Amd. No. Date of issue CommentsBS4856-3:1975 BSI 11-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Definitions 1 4 Operating conditions of

9、 units 1 5 Nomenclature 2 6 Object of the test method 3 7 Testing conditions 4 8 Instrumentation 4 9 Test equipment 5 10 Test facility 6 11 Air temperature measurement 7 12 Test method 7 13 Test method (air side measurements) 9 14 Calculations 9 15 Rating tests 11 16 Example 13 17 Sensible and laten

10、t cooling rating tests 15 18 Enclosure sweating tests and condensate disposal tests 17 Appendix A Heating units with fan installed downstream of the coil 19 Figure 1(a) Thermometer pocket for steam test 20 Figure 1(b) Thermometer pocket for hot water test 21 Figure 1(c) Thermometer pocket for use in

11、 vertical pipes over 75 mm diameter 21 Figure 1(d) Thermometer pocket for use in horizontal pipes over 75 mm diameter 22 Figure 2 Multi-junction differential thermocouple 22 Figure 3(a) Inverted U-tube manometer 22 Figure 3(b) Piezometer ring 23 Figure 4(a) Thermometer shield 24 Figure 4(b) Thermoco

12、uple shield 24 Figure 5 Inlet air sampling tube 25 Figure 6 Outlet air sampling tube 26 Figure 7 Steam test equipment 27 Figure 8 Water test equipment 27 Figure 9 Hot water test equipment (maximum water temperature above 95 C) 28 Figure 10(a) Arrangement A of test apparatus 28 Figure 10(b) Arrangeme

13、nt B of test apparatus 29 Figure 11 Temperature and total pressure probe 29 Figure 12 Air flow mixers 30 Figure 13 Inlet temperature measurement 31 Figure 14 Traverse stations 32 Figure 15 Definition of x 33 Figure 16 Pressure-flow characteristics 33 Figure 17 Heat transfer 34 Figure 18 Thermal effi

14、ciency 34 Figure 19 Water temperature correction factor heating 35BS4856-3:1975 ii BSI 11-1999 Page Figure 20 Water temperature correction factor cooling 35 Figure 21 Graph of Q nversus q arat (t fi t ai )=60 C 36 Figure 22 Graph of Q nversus m fat q ar =0.93m 3 /s 36 Figure 23(a) Graph of R aand B

15、versus q ar 37 Figure 23(b) Graph of R wmversus m f 37 Table 1 Steady state conditions 7 Table 2 Rating test for steam as primary fluid 12 Table 3 Rating tests for water or heat transfer fluid 14 Table 4 Latent cooling rating test series 15 Table 5 Enclosure sweat test conditions 17 Publications ref

16、erred to Inside back coverBS4856-3:1975 BSI 11-1999 iii Foreword Part 3 of this British Standard has been prepared under the authority of the Refrigeration, Heating and Air Conditioning Industry Standards Committee in response to requests from industry. The Committee acknowledge their debt to the He

17、ating and Ventilating Research Association for the Associations work in formulating the methods of testing which appear in this standard. These methods cover a range of testing conditions which encompass the complete performance envelope of the individual items of equipment. The general approach to

18、the test methods described has been to consider the simplest practical methods of carrying out the measurements without any unnecessary sacrifice of accuracy. The standard relates to equipment with capacities of up to the equivalent of75kW. Where reference is made to British Standards, and if no met

19、ric version is available (e.g.BS1042 “Methods for the measurement of fluid flow in pipes”, etc.), then the appropriate British Standard in imperial units shall be used in conjunction with BS350 “Conversion factors and tables”; attention is also drawn to BS3763 “The International System of units (SI)

20、”. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document compris

21、es a front cover, an inside front cover, pagesi toiv, pages1to38, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS4856-3:1975 BSI 11-

22、1999 1 1 Scope This Part of this British Standard deals with methods of carrying out thermal and volumetric tests on units intended for use with additional ducting containing fluid to air heat exchangers and incorporating their own electrically powered fan system. The units may be either for heating

23、 or for cooling applications and the latter may be with or without dehumidification under frost-free conditions. The tests are to be carried out on units in an essentially clean condition. 2 References The titles of the British Standards referred to in this standard are listed on the inside back cov

24、er. 3 Definitions For the purposes of this British Standard the following definitions apply. 3.1 fan coil unit a fluid-to-air heat exchanger apparatus through which air is passed by its electrically powered fan system and which is intended for general commercial use in the field of generating comfor

25、t conditions. This unit may or may not contain filters 3.2 unit heater and unit cooler a fluid-to-air heat exchanger apparatus through which air is passed by an electrically powered fan system and which is intended for general industrial use in environmental control. This unit may or may not contain

26、 filters 3.3 essentially clean conditions those conditions applying when further cleaning of a unit does not affect the rating figures 3.4 reference air conditions temperature 20 C; absolute pressure1.013bar 1) ; relative humidity43%; density1.200kg/m 3 4 Operating conditions of units 4.1 The aerody

27、namic performance of a ducted unit and consequently the thermal output is to some extent dependent upon the temperature and location of the heat exchanger. If a unit is to be used for a heating duty then temperature effects will be most significant if the fan is located downstream of the heat exchan

28、ger. The rating tests described in the standard are for heating units with the fan located upstream of the coil, and for cooling units with the fan in any position. If the fan is located downstream of the coil then for heating units the modified test series described inAppendix A shall be applied. 4

29、.2 The primary medium shall be any of the following fluids. a) Water. b) Steam. c) Heat transfer fluid (excluding volatile refrigerants). 4.3 The operating conditions of the units shall lie within the following ranges. a) Chilled water from2 C to20 C. b) Low temperature hot water from40 C to95 C. c)

30、 Pressurized water up to200 C. d) Heat transfer fluid from40 C to200 C. 4.4 The air volume flow rate of the unit shall lie within the range25 10 3 m 3 /s to5m 3 /s. 1) 1bar=10 5 N/m 2 =100kPa.BS4856-3:1975 2 BSI 11-1999 4.5 There is no restriction on the mounting of these units, provided that they a

31、re tested whilst mounted in a way representative of their intended use. 4.6 The requirements of the methods for individual tests may be followed to determine the performance of a unit at one specified set of conditions; where the performance at conditions other than those of the actual test are to b

32、e stated, the full schedule of tests specified in the standard shall be completed. 5 Nomenclature For the purposes of this British Standard the following nomenclature is used. Symbol Quantity Unit A D Area of test duct m 2 A i Area of air inlet duct m 2 A o Area of unit air outlet m 2 A s Surface ar

33、ea of insulated duct m 2 B Bypass factor c pa Specific heat capacity of air kJ/(kg K) c pf Specific heat capacity of primary fluid kJ/(kg K) c pw Specific heat capacity of water kJ/(kg K) H D Test duct hydraulic diameter m h ai Inlet air enthalpy kJ/kg of dry air h ao Outlet air enthalpy kJ/kg of dr

34、y air h b Enthalpy of saturated air at apparatus dew point kJ/kg of dry air k t Thermal conductivity of insulating material W/(m K) K f Temperature correction factor L Latent heat of evaporation kJ/kg l Thickness of insulating material mm M t Net mass of condensate formed during test kg M n Net mass

35、 of condensate formed during no-load test kg M f Total mass flow of primary fluid kg m a Air mass flow rate kg/s m f Primary fluid mass flow rate kg/s %p f Primary fluid pressure drop Pa %p fr Primary fluid pressure drop at reference temperature (cooling10 C, heating80 C) Pa p b Barometric pressure

36、Pa p br Reference barometric pressure (101325Pa) Pa p f Upstream static pressure at flow meter Pa %p F Flow meter pressure drop Pa p v Dynamic pressure of airstream Pa p vn Dynamic pressure at point n Pa p s Test duct static pressure Pa p d , p h , p B , p i Pressure loss corrections defined in14.3

37、Pa p sc Static pressure rise corrected for friction, etc. PaBS4856-3:1975 BSI 11-1999 3 6 Object of the test method The object of the tests is to establish the performance of the unit over a specified range of primary and secondary fluid conditions and room temperatures. The test procedures set out

38、in this standard are for the determination of: a) the gross and net thermal outputs; b) the secondary fluid flow rates; p so Static pressure rise corrected to unit outlet area Pa p sr Static pressure rise at reference conditions Pa Q n Net heat transfer kW Q o Heat losses or gains kW Q g Gross heat

39、transfer kW q a Air volume flow rate m 3 /s q ar Air volume flow rate at reference conditions m 3 /s q f Primary fluid volume flow rate m 3 /s q fr Primary fluid volume flow rate at reference temperature (cooling10 C, heating80 C) m 3 /s R Overall appliance thermal resistance K/kW R a Air side appli

40、ance thermal resistance K/kW R wm Water plus coil metal appliance thermal resistance K/kW R m Overall appliance thermal resistance at mid range air flow rate K/kW S Sensible to total heat ratio t ai Inlet air dry bulb temperature C t ao Outlet air dry bulb temperature C t ao Outlet air wet bulb temp

41、erature C t an Air dry bulb temperature at transfer point n C t F Temperature at flow meter C t fi Inlet primary fluid temperature C t fo Outlet primary fluid temperature C t s Saturated steam temperature C t b Ambient air dry bulb temperature C t ar Reference air dry bulb temperature at20 C C %t m

42、Logarithmic mean temperature difference C T t Duration of test s T n Duration of no-load test s %w Change in moisture content across coil kg/kg of dry air a Air density kg/m 3 ar Reference air density (1.2kg/m 3 ) kg/m 3 f Primary fluid density at mean fluid temperature kg/m 3 fr Primary fluid densi

43、ty at reference temperature (cooling10 C, heating80 C) kg/m 3 Symbol Quantity UnitBS4856-3:1975 4 BSI 11-1999 c) the primary fluid pressure drop; d) freedom from sweating on the unit enclosure or casework; e) adequate condensate disposal. 7 Testing conditions 7.1 Primary fluid, liquid. The unit shal

44、l be tested at a minimum of three primary fluid inlet temperatures. The selected temperatures shall cover the range of duty over which the appliance is to be rated, that is, to within10% at either end of the range. 7.2 Primary fluid, steam. Gauge pressures for the tests shall be selected such that t

45、emperature intervals are not greater than20 C, and that a minimum of three test points are obtained. The steam shall have a minimum of1.5 C superheat to ensure the absence of entrained moisture, and a maximum of3 C superheat. 7.3 Entering air conditions. The entering air temperature shall be within

46、the range15 C to25 C for heating and20 C to30 C for cooling. 7.4 Primary fluid flow rate. For duties quoted over a range of primary fluid flow rates, tests shall be carried out at a minimum of three primary fluid flow rates, spaced approximately equally over the required range and covering the range

47、 to within10% at either end. 7.5 Electrical supply conditions. The tests shall be carried out at the rated voltage and frequency of the unit which shall be stated in the test report. 7.6 Nominal rating. In the absence of a specified set of conditions, where a single nominal rating for either cooling

48、 or heating is required, the total capacity under the following conditions should be used: 8 Instrumentation 8.1 Steam 8.1.1 Temperature. Temperature measurement shall comply with the requirements of BS1041-2, BS1041-3 and BS1041-4. Thermometers, thermocouples and resistance thermometers shall be ca

49、librated to a precision of0.5 C against a NPL thermometer (accurate to0.25 C) and shall be used in pockets similar to those shown inFigure 1(a), situated at the entry and outlet of the unit between100mm and200mm from the unit connections. 8.1.2 Pressure. Pressure gauges shall comply with clause30 a of BS1780:1960. They shall be at least150mm in diameter and shall have a total scale range not more than three times the measured test