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႔ Chapter-7 Condensers and Evaporators
7-1
Chapter-7 Condensers and Evaporators
Refrigeration system component
( ) Cooling load refrigeration effect
( ) (continuous performance applications) frost control
(ဂ) Refrigerant
(ဃ) ၁ Direct expansion refrigerant unit ၂ Gravity ၊ pump recirculated ၊ flooded refrigerant ၃ Secondary coolant (brine, e.g., salt and glycol) ႔ ၍
( ) System efficiency
( ) Air cooled၊ water cooled condenser
( ) Compressor (open ၊ hermetic ၊ semi-hermetic motor drive ၊ reciprocating ၊ screw or rotary)
( ) System type (single stage ၊ single economized ၊ compound or cascade arrangement)
Condenser (၁) air cooled ၊ (၂) water cooled (၃) evaporative condenser ၍ Air cooled condeser ၍ ႔ ႔ water cooled condenser Evaporative condeser ၍ ႔
Chiller condenser heat exchanger Shell and tube ၊ shell and coil ၊ tube within a tube evaporative condenser Condenser
Condenser Condenser (size) (weight)၊ (weather conditions)၊ (location)၊ (availability of electricity) (availability of water) ႔
(process industry) condenser configuration condenser (criteria) (၁) Condenser heat capacity (၂) Condensing temperature and pressure (၃) Refrigerant coolant ႔၏ (flow rate) (၄) ႔၏ (design temperature for water and/or air) (၅) (operation period) (၆) (climatic conditions) ႔
Air conditioning refrigeration condenser ႔ (heat rejecting) (၁) Water cooled condenser
႔ Chapter-7 Condensers and Evaporators
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(၂) Air cooled condenser (၃) Evaporative condenser ႔
Commercial refrigeration water cooled air cooled refrigerant condenser (၁) Shell and tube ၊ blow-through ၊ horizontal air flow (၂) Shell and coil ၊ draw-through ၊ vertical air flow (၃) Tube in tube ၊ static or forced air flow ႔
Water cooled condenser (၁) Cooling load (၂) refrigeration (၃) cooling water ၏ (temperature) (quality) (၄) (amount of water) ႔
Shell and tube heat exchanger condenser Shell refrigerant tube chilled water ၊ glycol coolant Condenser shell ၏ (lower portion) liquid receiver T refrigerant T flash gas subcooler
Air cooled coil evaporative condenser ႔ auxiliary receiver cooler Fan (heat transfer rate)
၇.၂.၁ Condenser building service chilled water ႔ ႔ heat rejection equipment (၁) Air cooled condenser (၂) Water cooled with dry cooler (၃) Water cooled with open cooling tower (၄) Water cooled with closed cooling tower (၅) Evaporative condenser ႔
၇.၄.၃ Application ၊ Selection and Maintenance of Remote Air Cooled Condensers Remote air cooled condenser total heat rejection
Air cooled chiller water cooled chiller energy efficient Air cooled chiller water cooled chiller ႔၏ chiller ၏ efficiency system water cooled chiller condenser water pump cooling tower ႔ ၏
Condenser ႔ (heat rejection) condensing pressure
Chillers and Chilled Water Systems ႔
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Air cooled condenser (remote) (pressure drop) ဂ Cooling load
Condenser evaporator ၏ (pressure drop) flashing liquid line subcooling
Condenser compressor (gravity) refrigerant compressor ႔ Hot gas line ႔ ႔ (U ) Condenser ၏ upstream check valve
Air cooled chiller (maintenance) Coil ႔ refrigerant ၊ ဂ Air cooled condenser efficiency (manufacturer)၏ (guideline)
၇.၄.၄ Air Cooled Condenser Controls Air cooled condenser compressor ၊ fan
refrigerant ၏ Expansion Valve(TXV)၏ (pressure drop) ၍ air cooled condenser control
Air cooled condenser control (၁) Flooded Coil Condenser (heat transfer surface)
refrigerant control valve ၍ Receiver refrigerant (charge)
(၂) Fan Cycling fan fan ၊ ႔
၍ (minimum head pressure)
(၃) Dampers Discharge damper ၍ condenser fan ၏ (air flow) control
(၄) Variable Speed Fans Fan speed ၍ (air flow) control
40°F system fan cycling 0°F ႔ system fan speed control ႔ damper
႔ Chapter-7 Condensers and Evaporators
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Air cooled condenser (commercial application) ႔ ႔ air cooled condenser
၇.၅.၂ Common Configurations of Condenser evaporative condenser ( ) Forced-draft with axial fans ( ) Induced-draft with axial fans (ဂ) Forced-draft with centrifugal fans ႔
၇.၅.၃ Forced-Draft, Axial Fan Condensers ၇-၈(a) forced-draft axial fan condenser Fan
(end) ႔ (side) tube bundle ႔
Chillers and Chilled Water Systems ႔
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ၭ fan (၆) Fan (belt-driven) fan E fan ႔
(a) Forced-draft, axial fan condenser
(b) Induced-draft, axial fan condenser
၇-၇ Evaporative condenser ၏ diagram
၇.၅.၄ Induced Draft, Axial Fan Condensers Forced draft axial fan unit induced draft condenser Fan
႔ Fan (၄) Fan fan fan gear box
၇.၅.၅ Forced Draft, Centrifugal Fan Condensers Forced draft centrifugal fan condenser fan tube bundle ၏
႔ Fan (၈) Fan (belt-driven) fan (high-pressure) air flow Efficiency Evaporative cooling refrigeration system ႔ cooled fluid chiller ၏ shell and tube condenser
၇.၆ Evaporative Cooling
Evaporative condenser ၏ (characteristics) (၁) Circulating (၂) Water treatment system (၃) (Reduced space requirement)
Direct expansion evaporator refrigerant ႔ (evaporate) DX coil refrigerant 70% ႔ ႔ (evaporate) ၃၀% superheated temperature ႔ ႔
Chillers and Chilled Water Systems ႔
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DX coil liquid overfeed flooded coil fan power DX coil refrigerant flow control Refrigerant (flow) suction line ႔ refrigerant Compressor ႔ refrigerant Refrigerant (flow) refrigeration capacity evaporator efficiency
(၇-၁၉) direct-expansion (DX) shell-and-tube evaporator shell warmer water refrigerant tube
၇-၂၀ DX Evaporator tube detail ၇-၂၁ DX Evaporator
DX evaporator ၏ small temperature difference ႔ approach temperature flooded evaporator DX evaporator leaving water saturated evaporator temperature ႔ heat exchanger၏ Flooded evaporator
၇-၂၂ DX evaporator ၏ small temperature difference ႔ approach temperature
၇.၈ Evaporator Evaporator ႔ refrigerant
Refrigerant chilled water ႔ ႔ Evaporator refrigerant ၭ
chilled water (copper tube) evaporator
Approach temperature refrigerant chilled water ႔ (temperature difference Evaporator ၏ heat transfer efficiency ၊ approach temperature
႔ Chapter-7 Condensers and Evaporators
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Water chiller ၏ evaporator shell-and-tube refrigerant-to-water heat exchanger Chiller ၍ tube refrigerant ႔ chilled water
၇-၂၈ Condenser small temperature difference ႔ approach temperature difference
Leaving condenser water temperature refrigerant temperature (temperature) small temperature difference ႔ approach temperature (၇-၂၈) small temperature difference ႔ approach temperature (100°F-95°F=5°F)
Chiller refrigerant (direction of the flow of the refrigerant) ၍ dry expansion chiller flooded type chiller ၍
Approach temperature (၁) Condenser approach temperature (၂) Evaporator approach temperature (၃) Cooling tower approach temperature ႔
Approach temperature Approach temperature heat t medium ႔ fluid ႔၏
(heat) (high temperature) fluid (low temperature) fluid ႔ ႔ (heat t Approach Temperature Difference (ATD) ၍
Approach Temperature Difference (ATD) fluid ၏ fluid ၏ ၍
၇.၁၁.၁ Condenser Approach Temperature Chiller ၏ condenser refrigerant condenser water ႔
(heat t ႔ Condenser approach temperature chiller ၏ condenser refrigerant ၏ condenser condenser water ၏ Table 7-2 condenser approach temperature condenser refrigerant temperature (31.7°C @ 681.2Kpa) leaving condenser water (30.7°C) ၍ 1° - Trane chiller ECV6E 56 (HFC 134a) 9:45AM data Table 7-2 Chilled Water Set Point 6.7°C Leaving Chilled Water 6.7°C Entering Chilled Water 10.1 Entering Condenser Water 28.4°C Laving Condenser Water 30.7°C Active Control Set Point 100% Evaporator Ref Pressure 254.2Kpa
၇.၁၁.၂ Evaporator Approach Temperature Chiller ၏ evaporator chiller water refrigerant ႔ (heat
t ႔ Evaporator approach temperature chiller ၏ evaporator (leaving) chilled water ၏ chiller ၏ evaporator refrigerant ၏ Table 7-2 evaporator approach temperature leaving chilled water (6.7°C) evaporator refrigerant temperature (5.0°C @ 254.2Kpa) ၍ 1.7°
Table 7-3 evaporator DX Evaporator Flooded Evaporator Hybrid Falling Film Evaporator Water outside the tubes Water inside the tubes Water inside the tubes Refrigerant inside the tubes Refrigerant outside the tubes Refrigerant outside the tubes Water connection at side Water connection at ends Two bundles of water tubes Upper bundle is covered in a film of
refrigerant Upper bundle is flooded in the
refrigerant
၇-၃၀ Flooded chiller ၇-၃၁ Dry expansion chiller
၇-၃၂ Evaporator tube bundle ၇-၃၃ Evaporator coil with four fans
Chiller evaporator condenser ႔၏ approach temperature 2°C 2°C chiller (energy) leaving chilled water (6.7°C) evaporator refrigerant temperature evaporator refrigerant temperature chiller compressor ၍
႔ Chapter-7 Condensers and Evaporators
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၇-၃၄ Recommended piping components for typical evaporator installation