4 International Conference On Building Energy, Environment ... · Return air fan / exhaust airfan....

4th International Conference On Building Energy, Environment

Evaluation of air conditioning system design of swimming pool complex

H.S.Dalal

The Associated Engineering Partnership, Kuwait

ABSTRACT Air conditioning system design planning is very critical as it is multi-zone system based on different inside conditions and different humidity levels of different activity like competition, diving, recreational, spectators etc. Some areas require a positive pressure & some areas require negative pressure . For reduction of humidity in swimming pool area, minimum 4 Air change per hour as fresh air will be considered as recommended by ASHRAE ,(Application volume – Natatoriums) . Different type of energy recovery unit like Plate type Heat exchangers, Heat pipe etc will be considered . As air is contaminated with chlorine , Ducting material also is an important choice. Smoke ventilation also plays an important role in combination with air conditioning system design. Natural ventilation in combination with mechanical exhaust system. In this paper, an existing project related to student competition in Kuwait is presented . Different aspect of air conditioning system design is compared related to Energy consumption and Indoor air quality . KEYWORDS : PHE, ACH, ASHRAE, ERU, Nomenclature

PHE - plate type heat exchanger. ACH - Air change per hour. ASHRAE - American society of heating, Refrigeration and conditioning. ERU - Energy Recovery unit. VFD - Variable Frequency Drive.

INTRODUCTION The complex was designed based on student activity related to competition, training etc. Indoor swimming complex consists of swimming pool , Diving pool , offices of coach, lecture hall etc. Kuwait ambient conditions is very hot . based on locations of coastal the design conditions have been divided in two . interior area and coastal area – within 2 KM of coastal side . ( fig 1 An Image of Swimming Pool project-Paaet)

Fig 2 is a perspective view of swimming Pool of 200 spectators . As Kuwait conditions requires roof will have high thermal resistance say ( R-- 5-8 in S.I Unit ) approx , sandwiched panel of 100 mm polystyrene rigid type covered by high quality aluminium sheet both upper and lower have been considered. Circular type Supply duct , circular type return duct are placed within space frame and suitable diffuser - swirl type / jet type etc are connected . Smoke ventilation are designed in combined with Air conditioning system. Fresh air is taken by opening automatic door and mechanical exhaust are considered with Return air fan / exhaust airfan.

DESIGN The location of this project is within 2 KM of coastal area. Swimming Pool design considers Wet Bulb prioritization as latent load dominates in cooling load. Considering 2.5 % frequency , the DBT-- 43 deg C, WBT—31.8 deg C. The following areas are considered in swimming pool

complex.

Type of Space

Summer , ( db, % rh)

Winter , ( db, % rh)

Swimming Pool

27 Deg C, 55 % 21.1 deg C, 30% rh

Office 24 deg C, 50 % rh 21.1 deg C, 30 % rh.

Kitchen 27 deg C , no control on rh.

Evaporation load for swimming pool and diving pool is very large . The total cooling load is approx 400 TR. The latent Load becomes high. Humidity plays an important role. Fresh air is delivered after dehumidifying via cooling coil in Fresh air unit where plate type heat exchanger placed between return air and fresh air to get an energy benefit. (refer Fig3) . Based on air contamination , the swimming pool area have been kept as negative pressure whereas spectator area have been kept as positive pressure . keeping little high velocity for air discharge in spectators area it is possible to work like air curtain .

ISBN: 978-0-646-98213-7 COBEE2018-Paper270 page 803


AIR DISTRIBUTION Outside air is passed in Energy recovery unit ( Plate Type Heat Exchanger) and then cooled to 35 deg C to get mixing temp at 31 deg C in AHU . The outside air is approx ( 20 % - 25 % ) . The AHU- swimming Pool is also taking care of spectator area and air barrier ( theoretically) by throwing air at velocity @2.5- 2.8 m/s. To keep swimming pool area as negative , the exhaust air have been considered as 110 % of supply air and Return duct is performing as both smoke exhaust and air conditioning. ( refer Fig 2) . 4 no AHU with matched Fresh air units have been considered. The return air quantity is approx 240,000 CMH. During smoke , considering the area as two zones , the exhaust air quantity requirement as 300,000 CMH. The return air fan have been kept two in situ so that during smoke it can deliver 240,000 x2 = 480,000 CMH.

DESIGN MODIFICATION STUDY Air distribution pattern change

The air distribution pattern in spectators area can be done via underseat. This will improve the air quality for breathing and as the space volume is reduced , the cooling requirement will be decreased by 15 % and in return this will save energy. See ref sketch of swimming pool existing project . Modifying the chiller capacity based on Temperature

The Air Handling units for swimming pool is serving spectators area also . The supply air temperatures for swimming pool area and spectator area is different so it will be difficult to control the chilled water temperature as the Chiller is same. Refer Fig 4 describes the operation . constant primary pumps and variable secondary pumps are serving the operation. De-coupler is managing the variation of water flow and based on flow direction , sequencing of Chiller is established. Refer Fig 5 describes the Chiller schematic of swimming pool area with separate AHU in swimming pool area. The cooling capacity have been modified.Chillers of different Leaving Temperature have been considered which will reduce the capacity of the Chiller. Due to this change, the secondary pumps can be deleted. Primary pump will be considered as variable flow and an Automatic control valve will be put so that priming should be established in the pumps. Refer Fig 6), describes the Chiller schematic of spectator area and office area having separate AHU for spectator area and also office area as before. The cooling capacity have been modified. Separate Chillers have been considered .other parameters will be same as before. Calculation

Calculation was done using carrier HAP software. Heat loads are related to building heat gains due to outdoor air,

lighting, walls , roof , wall, glass. As Kuwait outdoor air temperature is very high and also humid, special insulations have been considered in walls and roof, Roofs are pre-insulated KerbyType pre insulated panel of alumina upper portion and also lower portion with 1.5 mm thick. The internal latent loads in swimming pool are due to spectators, swimmers, and mainly due to evaporation of water. The evaporation loads are dependant on Pool characteristics such as surface area of pool, wet decks, water temperature and activity level of the pool like competition, leisure etc. The Evaporation rate ( wp in kg/s ) can be estimated for pools of normal activity levels, ( Smith et al,1993) (ASHRAE Application 2007, 4.6 ) .

Wp = A ( pw-ps) ( 0.089 +0.0782V) / Y --------- Where , A = Wet area of pool surface, m2. Pw = saturated vapour pressure taken at surface water temperature, KPA Ps = saturation pressure at room dew point, KPA V = Air velocity over water surface, m/s. Y = Latent heat required to change water to vapour at surface temperature, KJ/KG. Fresh air : Minimum will be as per ASHRAE standard 62.1 , @ 2.5 l/s / m2. Of pool. And wet deck area. Spectator -- @ 7 L/S per person. Supply air – based on supply temp as 16.5deg C. ( based on sensible load as well as latent load ) . To maintain room temp in swimming pool 27 deg C , heater will add heat and indirectly add cooling load.

RESULTS Schedule of Chiller

Designation

TR Cooler L/S

Ch, Power ,KW

Ent / leav T degC

Remarks

CH-01 440 52.0 440 6--13 Fig-4

CHSWM-01

245 34 230 7.5 --13

Fig -5

CH-Off-02

165 19.6 165 6--13 Fig 6

Schedule of Pumps

Designation

Water quantity, L/S

H, M

P, KW

Drive

Remarks

CHWP-01

52.0 12 11 CONST Fig-4

CHWS-01

61 25 25 VFD Fig-4



CHWS-02

16.7 25 7.5 VFD Fig-4

CHWP-SW

37.7

32

25

VFD

Fig -5

CHW

P-OFF

20.5 32 15 VFD Fig 6

Schedule of Fresh Air Units

Energy Comparison :

Schedule of AHU

DISCUSSION : The above study shows that separation of two areas based on temperature like swimming hall and other areas as explained in Fig 5 & 6 will reduce cooling load as well as energy. Regarding Capital Cost , addition of chiller willbe counter balanced by deletion of secondary pump and also due to saving in running cost within 3 years.

CONCLUSION : The Modified design will provide better controllability.

ACKNOWLEDGEMENT : The Fig 1 Image have been taken from PAAET site.

REFERENCES

1) Existing project picture taken from site. 2) M.E.W regulation related to outdoor and indoor

conditions. MEW- R- 6, 2014 edition. 3) ASHRAE APPLICATIONS – Natatoriums , A 4.6 . 4) ASHRAE , april, 2012 – Randy C.Barter –

Designing for IAQ in Natatoriums. 5) John W.Lund , Geo Heat Center – Design

Considerations for Pools and SPAS ( Natatoriums) .

Designation

F.AQty, L/S

X1000

Ex A

Qty, L/S X1000

FAF ,

KW

Exh F, Power

KW

Type Remark

FAF- S-1,2,3,4

4.7 6.2 7.5 5.5 Plate

Fig4

FAF- O-1,2,

2.8 2.5 5.5 3.7 wheel

Fig4

FAF- SW-

1,2,3,4

4.1 5.3 7.5 5.5 Plate

,Fig 5

FAF- OFF- 1,2

3.75 3.4 5.5 3.7 wheel

, Fig 6

DescriptIon

Chiller ,KW

AHU &FAU,

KW

Pump,KW

Total,KW

Remark

Existing

440 191 43.5 674.5 Difficult for temp control

Modified

395 185 40 620 Better controlla

bility

Designation

S.AQty, L/S X1000

R.AQty L/S X1000

LOAD, TR

S.A.F Power, KW

ELE, KW

R.A.F power, KW

Remarks

SW-1,2,3,4

15.1 16.6 75 30 40 15 Fig--4

0FF-1,2,3

7.5 6.5 40 11 0 0 Fig--4

SW-1,2,3,4

12.7 14 60 25 0 11 Fig -5

0FF-1,2,3,4

7.5 6.5 40 11 0 0 Fig 6



Fig 1: An Image of swimmimg Pool Project , PAAET.

Fig 2: A schematic view of swimming pool



Fig 3 A typical view of AHU – swim and matching FAU

Fig 4. Equivalent Exisiting scheme of chilled water Circuit.



Fig 5 . Modified Chilled water circuit for Swimming Pool Hall.

Fig 6 Modified chilled water circuit for other area .


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