Airex University VAV Applications Displacement Ventilation

Transcription

1 Airex University VAV Applications Displacement Ventilation Jim Aswegan Chief Engineer Copyright Titus 2015 All rights reserved

2 Discussion Items Terminal Unit Systems Single Duct Dual Duct Fan Powered Terminal Unit Options TU Applications & Sizing

3 The Terminal Unit System CONTROLLER / ACTUATOR DAMPER THERMOSTAT VELOCITY SENSOR THERMOSTAT Measures the air temperature in the space VELOCITY SENSOR Measures the airflow through the unit CONTROLLER /ACTUATOR Receives input from Velocity Sensor / Thermostat, calculates output to Actuator DAMPER Modulates to control space temperature

4 Flow Sensor Inlet of the terminal Senses amplified velocity pressure which is converted into an electric output in the controller Multi-point center averaging sensor Accurate to +/-5% of any airflow range Provides accuracy no matter the inlet conditions TU TU TU

5 Single Duct ESV Cooling only - interior zones Single duct with reheat - perimeter

6 Single Duct ESV Cooling Only Supply Discharge Hot Water/Electric Coil Cooling / Reheat Supply Discharge

7 Dual Duct System Hot and cold air is blended in unit Provides simultaneous heating and cooling of zones throughout building All air is filtered Air Handling Unit Dual Duct TU

8 Dual Duct Common Applications Typically used in hospitals and universities Hospitals: For clean air vs. fan powered ceiling plenum heat Universities: For lower sound vs. fan powered terminal units Up to twice the cost of single duct systems Dedicated outside air systems (DOAS) Rising in usage Larger capacity unit needed to overcome pressure drop Requires an access door upstream of the heating coil

9 Fan Powered Terminals Overview Two basic types Series fan Parallel fan Both utilize heat recovery Recirculate ceiling plenum air

10 Titus Fan Powered Terminals TQS / TFS / FLS - Series Fan Power Terminal Units TQP / FLP - Parallel Fan Power Terminal Units

11 Series Fan Terminal Overview Advantages Perceived improved room air motion due to constant volume Constant sound source Used in high profile, sound sensitive applications Disadvantages Operates continuously Larger fan motor since sized for cooling requirements

12 Series Fan Power Terminal Unit Air path in series with primary Lower inlet static because air only needs to be delivered to the fan Primary Air Return Air Fan Discharge

13 Series Fan Power Terminal Unit TFS-F FAST TM attenuator Ships internal to the unit Spring clip design/no tools required Shaft down motor Eliminated the need for fan packing Enhanced reliability Lance and tab Motor/ Blower Assembly Faster/easier removal for maintenance staff FAST TM Attenuator Return Air

14 Parallel Fan Power Terminal Overview Advantages Smaller fans sized only for heating loads Utilizes wasted plenum heat from lights Disadvantages Noise objections from cycling fans

15 Parallel Fan Terminal Designed for intermittent operation of fan during heat cycle only Smaller fan required - sized only for heating volume During cooling cycle, fan is off, box acts like single duct Primary Air Discharge Air Return Air Fan Back draft Damper

16 Series vs. Parallel SERIES Constant room air motion due to constant fan Constant sound level Lower system pressure requirements ( w.g.) PARALLEL Fan runs during heating only Smaller motor/blower Variable sound level and air volumes Used in high profile, sound sensitive applications Primary Air Return Air Fan Discharge Air Primary Air Return Air Fan Back draft Damper Discharge Air

17 Options Liners Heat Motors Controls

18 Linear Types (Insulation) ½" and 1" Fiberglass (standard) ½ and 1 EcoShield Matte and Foil Face Fiber Free SteriLoc UltraLoc (Dual Wall)

19 Fiberglass ½" and 1" fiberglass Industry standard liner Dual density Typically not specified for hospital or IAQ applications

20 EcoShield Titus Standard ½ and 1 Cotton Liner (recycled denim) Contains no fiberglass Does not itch or irritate the skin No outgassing or (VOC) concerns Meets all the same req. as fiberglass

21 Fiber Free ½ and 1 EPFI (Engineered Polymer Foam Insulation) Contains no fiberglass Cleanable surface Low thermal conductivity Very low vapor transmission

22 SteriLoc Foil face duct board 7/8 thick fiberglass Foil facing provides cleanable surface Sound penalty for reflective surface All edges encapsulated Hospital and IAQ applications

23 UltraLoc Dual wall liner has 1 fiberglass encapsulated within a metal liner Units are much heavier Sound penalty due to inner metal lining Specified for cleanable surface

24 Reheat Coils Hot water coils Electric coils Coils are typically selected at the minimum CFM Per ASHRAE discharge temperature + 15 F <= room air temperature

25 Hot Water Coils Standard (10 FPI) or High Capacity (12 FPI) Pressure tested to 450 psi Located on the discharge side of the Single Duct and Series Fan Powered units Can be on inlet or discharge of Parallel Fan Powered units Adds pressure drop Factor into downstream static

26 Standard Electric Heat Option Standard 3-stage heater 1 st Stage: 33% 2 nd Stage: 67% 3 rd Stage: 100 %

27 SCR Electric Heat Time proportioned One stage of heat modulated based on a PWM signal Provides heat based on room load

28 Lynergy Electric Heat Time proportioned Silent, rapid response solid-state relays Optional Discharge Temperature Sensor PWM Output Actual Room Heat Load Room Heat Requirement 100% 80% 60% 40% 20% 0% Off Pulse On Duration of Pulse

29 Terminal Unit Controls Pressure dependent Volume dependent upon static pressure, no flow limits No velocity sensor or controller required Thermostat and actuator only Can t meet modern ventilation codes

30 Terminal Unit Controls Pressure independent Volume independent of static pressure (as long as minimum pressure available) Velocity sensor required Thermostat, controller and actuator Minimum and maximum flow limit adjustment

31 Terminal Unit Controls Pneumatic controls Pressure dependent or independent Requires compressed air system Moderate installed cost (compressor/maintenance)

32 Terminal Unit Controls Analog electronic controls Pressure independent High accuracy Low installed cost Easy setup - adjustments made at thermostat with screwdriver

33 Terminal Unit Controls Digital electronic controls Pressure independent Communication capability - dynamic changes possible System integration into BAS High installed cost (network wiring, hardware, software, commissioning, user training)

34 Terminal Unit Sizing How to size and select terminal units Single duct terminals Series / Parallel fan box terminals Electric Heat sizing

35 Single Duct Sizing When selecting a box, don t choose a box that is near the top end of the requirement No room for expansion Size for maximum inlet velocity of 2000fpm Allows for typical minimum inlet velocity of fpm This guarantees easy and accurate damper control

36 Fan Curves Fan performance is dependent on changes in system pressure Minimum - fan performance at lowest turndown Maximum - fan performance at highest voltage

37 Inlet Selection Determine inlet size based on cfm requirements When selecting a box, don t choose a box that is near the top end of the requirement No room for expansion Size for maximum inlet velocity of 2000fpm Reduce sound concerns Allows for typical minimum inlet velocity of fpm This guarantees easy and accurate damper control CFM Inlet Size Range x

38 Series Fan Box Sizing Select fan at 75% of maximum capacity Select fan for cooling load

39 Parallel Fan Box Sizing Select fan at 50-75% of maximum capacity Select fan for heating load

40 Oversizing Issues Most fan box problems caused by oversizing for sound Motor efficiency drops, motor runs hotter, rapid bearing wear, reduced service life, etc. Not necessarily quieter! Motor hum from lower PSC motor speeds

41 Oversized Terminals Oversized inlets cause problems Limited damper motion Minimum flow control problems Excessive temperature rise for reheat

42 Electric Heat Rules Minimum kw determined by smallest wire gauge we can use and voltage Maximum kw determined watt density and current draw Minimum airflow is determined by minimum velocity pressure to close airflow switch 45 F max temperature rise across heater 70 CFM/kW

43 Motor Options PSC motors (SCR controlled) / ECM motors / Manual PWM Remote PWM

44 Terminal Unit Motors PSC motors ECM motors Speed controllers Fan curves

45 Standard PSC Motors Typically specified as highefficiency motor Only when compared to other induction motors Efficiencies from 20 to 60% depending on turndown Fan speed is controlled by SCR

46 SCR s Speed controlled by SCR (Silicon Controlled Rectifier) A switch that chops the effective voltage to the motor Does not directly control torque Low cost Works well for most applications

47 ECM Motor Electronically Commutated Motor

48 ECM Benefits Properly developed motor holds constant cfm regardless of changes in static pressure Motor will compensate for dirty filters, etc. Soft start Motors are set to start up slowly, less wear and tear, quieter No wearing of brushes Motor life is ~90,000 hours (30 years of typical series fan powered terminal life vs. 50,000 hours for PSC motor)

49 ECM Speed Controllers Manual PWM speed control Provides manual adjustment dial with duty cycle % and live RPM readout Remote PWM speed control Accepts 0-10 VDC speed control signal

50 ECM vs. SCR Watt Comparison TQS 0.20 Sp Watts ECM PSC cfm

51 ECM Energy Savings 350 watts savings =.350 kw 250 days/year x 12 hours/day = 3000 operating hours/year.350 kw x 3000 hours = 1050 kwh 1050 kwh x $.10* per kwh = $105 per unit per year energy savings!

52 ECM Fan Curves ECM provides constant volume with changes in pressure 52 Fan curves show constant volume range

53 VAV Diffusers (T 3 SQ)

54 T 3 SQ-4 Thermal Description Thermally powered variable volume diffuser Mounted in the popular OMNI diffuser Maintains space temperature Available in heating/cooling auto-changeover configuration 54

55 T 3 SQ-4 Thermal Parts Backpan Thermal Actuator Control Disc Venturi Tube Induction Channel Face Plaque Induction Cap

56 Face Plaque OMNI plaque with center induction cap Operation instructions and UL listing are on the back of every plaque

57 Plaque Assembly Unit will ship fully assembled to the plaque Install backpan only

58 T 3 SQ-4 Thermal Operation Room sensing element located behind induction cap in center of diffuser panel Control disc position varied by wax filled thermal element Wax cools down the actuator assembly retracts under the action of a return spring 58

59 T 3 SQ-4 Operation 59

60 Induction 60

61 T 3 SQ-2 Electronic Diffuser Digital electronic, plug & play Interchangeable master/drone configurations BMS Interface Stand-Alone networked Lonworks BACnet

62 T 3 SQ-2 Parts

63 Plaque Assembly OMNI plaque with induction channel and one-piece actuator/control disc assembly Supplied with actuator cable

64 Backpan Modified OMNI backpan Plug-n-play wiring box Unit ships without actuator connected to backpan

65 Wiring Interface Box

66 Control Module / Room Sensor Control module/room sensor Every must have a control module/room sensor 7 day programmable Override capabilities

67 Power Supply Module 120V / 24V transformer 208V / 24V transformer 277V / 24V transformer 1 RJ-9 connection 2 (4 pin) Mini-fit plenum cable Line voltage field wired

68 Master Communications Module (MCM) Available in three platforms: Stand-Alone LonWorks BACnet 4 Channels 15 diffusers per 60 total

69 Master Communications Module (MCM) Information collected per diffuser: Room Temperature Supply temperature Flow rate per diffuser Night Setback Facility Control disc position

70 Optional Inlet Heater Mounts diffuser neck Requires line voltage 120V, 208V or 277V 2 Thermal cutouts Airflow proving switch ETL Listed

71 Inlet Heater Powered via separate circuits. Enables Sub-metering Sub-metering via BMS Individual offices and individual diffusers Measurable heating cost on individual diffuser or group of diffusers

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73 Displacement Ventilation Systems Comfort & Contaminates Basic Concepts & System Benefits Outlet Types and Air Patterns Example Space Layouts Displacement & LEED

74 2015 Application Ch. 57 Fully Mixed Fully Stratified G.R.D. Displacement

75 Graphic Comfort Zone ( ) Met Rate Data based on ISO 7730 And ASHRAE Std. 55 Upper Recommended Humidity Limit humidity ratio DPT < 62.2 F 1.0 Clo 0.5 Clo Met Rate Operative Temperature F

76 Temperature Gradient ASHRAE Standard

77 Cooling Supply Air F ( C) Heating F ( C) Uniform Temperature

78 Fully Mixed Air Distribution Mixed Contaminates

79 Cool Air Supply Only 60 F - 68 F (16 C - 20 C ) Low Velocity < 70 fpm (0.36 m/s)

80 Fully Stratified Air Distribution Light Weight Contaminates Removed

81 Displacement Ventilation Basic Concepts & System Benefits

82 Adjacent Zone

83 Discharge Air Patterns

84 Standard Air Patterns Adjusted Air Patterns

85 Basic Concepts & System Benefits Low Energy ( < 0.04 Ps) (10Pa) Air Change Effectiveness (Std. 62.1, Ez = 1.2) Quiet Operation (< 25 NC)

86 Displacement Cooling

87 Displacement Stratification

88 Low Energy Higher equipment efficiency Uses warmer supply air 65 F (18 C) compared to 55 F (13 C)

89 Low Energy Lower horsepower fans 0.04 in. pressure (10 Pa) is required for proper diffuser performance Results in lower horsepower fans required = Fan Energy Savings

90 Displacement & Energy Savings Higher equipment efficiency 65 F compared to 55 F Higher discharge temperature reduces energy consumption IEER Temp (off coil) Nom Tons Annual KWH % Energy Savings º 50 92,308 base line º 25 46, % º 50 66, % º 25 33, % Calculations assume 2,000 annual run hours per year and 50% RH in space return

91 Fan Energy Savings with Displacement Cost of Pressure Supply Total Electricity Annual Diffuser Type Airflow Pressure cost Tp cost (cfm) (Tp) 0.08/KW per diffuser 3-cone 3-Cone Ceiling (TMS) Diffuser 0.06 $0.94 Sq. Plaque Plaque Face Ceiling (OMNI) Diffuser 0.09 $1.41 Louvered (TDC) $0.08 $1.72 Louver Face Ceiling Diffuser Perforated (PAS) 0.18 $2.81 Perforated Face Ceiling Diffuser DVRI $0.78 Displacement Diffuser Ceiling diffusers: 24 x 24, 10 inlet Displacement diffuser: 24 x 79, 10 inlet

92 Improved Ventilation ASHRAE Standard Ventilation for Acceptable Indoor Air Quality Zone Air Distribution Effectiveness, E z Overhead Cooling System = 1.0 Displacement Ventilation = % Less Fresh Air Required

93 HVAC System Benefits Heat sources outside the stratification layer are not considered in airflow calculations

94 Return Air Outlet located at ceiling level Allows heat from ceiling lights to be returned before it is able to mix with occupied zone

95 Humidity Issues Supply system must reduce relative humidity to less than 60% to meet IAQ concerns If 55 o F (13 o C) supply air is used for dehumidification, return air can be mixed with supply air to achieve 65 o F (18 o C) air

96 Return Air

97 Perimeter Heating Perimeter heating can not be accomplished with traditional displacement ventilation Separate system required in most applications: Dual Chamber Diffuser

98 Dual Chamber Diffuser Dual chamber plenum Dual chamber diffuser Displacement cooling Mixed-air heating Actuated diverter (24V) Displacement diffuser cooling Separate Discharge for Heating

99 Low Level Mixed Heating

100 Ideal Applications Ceiling Height > 9.0 ft. (2.75m) Open Plan Offices Casinos Theaters & Auditoriums Schools

101 Displacement Ventilation Advantages Smaller cooling power for desired room temperature in the occupied area Improved air quality in occupied area Longer periods of free cooling

102 Application Examples Poor Applications Room height < 9 ft. (2.75m) Surplus heat is the main problem not air quality In combination with mixing systems Office/rooms with cubicles Spaces with heavy contaminants

103 Displacement Ventilation Disadvantages Risk of draft due to placement of the diffusers Wall mounted devices often occupy large wall areas Stratified air becomes uncomfortable when cooling load exceeds ~30 Btu/hr/ft 2 (0.095/kW/m 2 ) Cannot heat with displacement ventilation

104 Temperature Gradient Ceiling Height 9 (2.75m)- 14 (4.25m) 50% Rule is applied 62 F 72 F 82 F 10 F - 10 F (Displacement ventilation, REHVA)

105 Temperature Gradient Ceiling Height > 14 (4.25m) 33% 67% 33% Rule 64 F 72 F 86 F 8 F - 14 F (Displacement ventilation, REHVA)

106 Displacement Ventilation Types of Outlets & Distribution Patterns

107 Displacement Diffusers Rectangular Mounts in wall 1 way pattern

108 Displacement Diffusers Rectangular Rectangular In wall, flush or floor mount

109 Displacement Diffusers Rectangular 3-Way Rectangular In wall, flush or mount floor 3 way pattern

110 Displacement Diffusers Rectangular Curved Face Flush or floor mount 3 way pattern

111 Displacement Diffusers Rectangular Stair Riser Steps, Stair Risers applications Great for auditoriums, concert arena s, and lecture halls

112 Displacement Diffusers Circular Column or floor mount 360º discharge

113 Displacement Diffusers Semi-Circular 180º Sidewall or column applications 180º pattern

114 Displacement Diffusers U shaped Semi-circular with straight sides 3 way pattern

115 Displacement Diffusers Corner w/ Curved Face Corner mount applications 2 way pattern

116 Displacement Diffusers Corner/Flat Face Corner mount applications 2 way pattern

117 Displacement Ventilation EXAMPLE Space Layouts

118 Private Perimeter Office Perimeter Wall

119 Open Plan Interior Office

120 Interior Break Room Round Outlets

121 Perimeter Conference Room Outside Wall

122 School Classroom Perimeter Wall

123 ASHRAE Standards for LEED ASHRAE 62.1 IEQ Prerequisite 1: Minimum IAQ Performance IEQ Credit 1: Outdoor Air Delivery Monitoring IEQ Credit 2: Increased Ventilation IEQ Credit 6.2: Controllability of Systems: Thermal Comfort (for naturally ventilated spaces) ASHRAE Standard 55 IEQ Credit 6.2: Controllability of Systems: Thermal Comfort IEQ Credit 7.1: Thermal Comfort: Design IEQ Credit 7.2: Thermal Comfort: Verification

124 Displacement Ventilation & LEED Minimum Energy Performance: EAp2 Optimize Energy Performance: EAc1 Minimum Indoor Air Quality Performance: IEQ p1 Increased Ventilation: IEQc2 Thermal Comfort Design: IEQc7.1

125 Publications HVAC Applications Handbook, Chapter 57 (ASHRAE, 2011) Fundamentals Handbook, Chapter 20 (ASHRAE, 2013) System Performance Evaluation and Guidelines for Displacement Ventilation (ASHRAE, 2003) Displacement Ventilation in Non-Industrial Premises (REHVA, 2002)

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128 LSC Terminal Unit Series fan powered terminal unit featuring a SENSIBLE COOLING chilled water coil. Designed to be part of a dedicated outdoor air system (DOAS) DOAS provides an alternative solution to addressing ASHRAE 62.1 ventilation requirements 12

129 LSC - Configuration Control Enclosure Hanging Brackets (Optional x4) Primary Air Inlet c/w: Aerocross Damper ECM Motor Sensible Cooling Coil ( + Heating Coil Optional) DWDI Blower Electric Heater (Optional) Return Air: Non Ducted Ducted (Optional) Filter MERV8 (Optional) Condensate Pan ECOSHIELD STD ½ Liner

130 LSC - Configuration Primar y Air Return Air LSC Terminal Unit Multiple Discharge Grilles

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132 SOLUTION FOR SCHOOLS Displacement, chilled beams and radiation principles. Induction Nozzles Tempered and dry primary supply air delivered at 55ºF Induced room air and mix to discharge air at appropriate temperature Heat Transfer Coils Room air induced through coils Sensible load handled by the coil Eliminates separate Heating system

133 TAO Section View

134 TAO: Cooling mode operation Cooling Mode Supply Airflow (70 to 71 ºF) Return Air 100% Exhausted Primary Airflow (55 to 58ºF) Chilled Water Room Air (75ºF) Supply Airflow (62 to 63ºF)

135 TAO: Heating mode operation Heating Mode Exhausted Supply Airflow (85-92ºF) Optional Heat Recovery Primary Airflow 450 CFM (62-66ºF) Room Air 900 CFM (70-72ºF) Supply Airflow (67-70º F)

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138 Potential for Increased Economizer San Francisco 55 F = 158 Days: 65 F = 365 Days: 207 Difference Dallas 55 F = 107 Days: 65 F = 177 Days: 70 Difference Chicago 55 F = 209 Days: 65 F = 263 Days: 54 Differenc (based on average daily temperatures)

139 Dual Duct Types Different designs for different mixing requirements Non-Mixing Standard Mixing High Mixing

140 Mixing Characteristics EDV (Non Mixing) - 1:10 For 10 F EAT Variance, there is 1 F differential 4 duct diameters downstream MDV (Mixing) - 1:20 Higher Ratio Sound Penalty

141 Dual Duct Terminal Unit Mixing Cold Supply Hot Supply Blended Discharge Non-Mixing Cold Supply Hot Supply Cold Discharge Hot Discharge

142 Thank You!