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Chilled water piping basics
The document discusses the key components and operation of chilled water systems. It describes the main components as chillers, cooling towers, pumps, piping and air handling units. It then covers topics such as chiller types, flow calculations, recommended flow velocities, chiller efficiency ratings, expansion tanks, piping basics including materials and valves used, and testing and balancing (TAB) of the system.
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Chilled water piping basics
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- 5. CHW SYSTEM COMPONENTS 1. CHILLER–AIR COOLED , WATER COOLED 2. CHW PIPING 3. PUMPS 4. COOLING TOWER (FOR WATER COOLED) 5. AHUS
- 6. CHILLER BASICS 1. Chilledwater flows thru the evaporator .The evaporator is a heat exchanger 2. Chiller compressor may be centrifugal, scroll, screw or reciprocating 3. The condenser may air cooled or water cooled 4. There can be multiple chillers in a chw plant
- 7. FLOW CALCULATION 1. Commondesign condition is supply water 44 F ,return water 54 F temperature difference 10 F 2. Q = W*C*DELTA TEMP WHERE Q = qty of heat exchanged (btu/hr) C = Specific heat of fluid (btu/lb F) W = Flow rate of fluid (usgpm) For water TR = FLOW* GPM* DEL T/24
- 8. FLOW VELOCITY 1. Toolow flow rate affects chiller efficiency 2. Too high flow rate cause vibration noise & tube erosion 3. The recommended flow rate is between 3- 12 fps
- 9. CHILLER EER 1. Chilleris the largest single point electriccity user in a building 2. EER = TR * 12/kw input 3. The recommended flow rate is between 3- 12 fps 4. Chillers rarely work in full load condition (2 %) hence NPLV is very important
- 10. EXPANSION TANK 1. Essentialto manage the thermal expansion 2. Can be open type or closed type 3. Open tanks must be located above the highest point 4. Air water interface or diaphragm tank can be located anywhere in the system 5. The lower the pressure in the tank the smaller it is
- 11. PIPING BASICS 1. Oncethrough & re circulating 2. Open & closed type 3. Friction loss in pipe will depend up on Velocity Interior surface roughness Diameter length 4. For long run pipes expansion joints are provided 5. the pressure in the tank the smaller it is 6. The chw Pipes should be insulated
- 13. PIPING BASICS 1. Pipingis usually steel, copper or plastic 2. Usually closed loop 3. Cooling tower piping is open loop 4. Generally the static pressure is less than 150 psi 5. If the system is above 150 psi static intermediate HE or chw systems are used
- 14. PIPING VALVES 1. 2way or 3 way valve to direct/by pass the flow 2. Balancing valve to control the flow 3. Gate valves for isolation 4. Globe valves for throttling 5. Butterfly valves – Isolation, throttling 6. Strainers- For filtration 7. Flexible bellows –Vibration arresting 8. NRV-at pump discharge 9. Pressure & temperature gauges
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- 22. 2 WAY &3 WAY VALVE
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- 24. TAB BASICS 1. HVACPiping testing procedure Pressure testing Evacuation Gas charging 2. Water pipe ling is balance with balancing valves 3. Air side balancing done by vcd s & dampers
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