[AC] 問﹕Chiller 有邊幾種？有別有啲乜特點？

答﹕

首先講大分類，Water Cooled Chiller & Air Cooled Chiller
最大分別係佢地個Condensor散熱方式，前者係用水散熱(連住Set Cooling Tower)，後者用風散熱。
Water Cooled Chiller好處係COP高，即係Operating Cost低得多；但同時佔地多，initial cost高，Cooling Tower要用水，泵sets等部件多咗意味住可靠性都低咗maintenance都複雜咗。


之後再以Comperssor分類Reciprocating Chiller / Screw Chiller / Centrifugal Chiller，Water Cooled Chiller & Air Cooled Chiller 都可以用呢啲Compressor



用唔同Compressor，以致個Cooling Capacity/COP都唔同

	Reciprocating	Screw	Centrifugal
Air Cool Capacity	Lower than 1500kW
Air Cool COP	Around 3
Water Cool Capacity	35-700kW	100-2100kW	350-4000kW (380V) 20000kW (11kV)
Water Cool COP	Around 5		Around 6
Characteristic	Relatively higher noise & vibration, 小型用	中型至大型	大型

For min. COP requirement, your can refer EMSD BEEO 2018 Edition, 以上都只係個方便記既約數。如果有落VSD的話，Air cooled 加1 咁上下，Water cooled 加1.5-2

Heat Pump refer http://elvissharing.blogspot.com/2020/03/ac-heat-pump.html

 Energy Saving Consideration:
- 加VSD，Air cool 同 Water Cool 都用得，high initial cost for device & control, part load上表現好
- Oil Free Compressor, Air cool 同 Water Cool 都用得，high initial cost for device & control, Integrated Part Load Value IPLV & Full Load 都比傳統Chiller好，有study say 慳電30%
原理﹕
Air Bearing - 個Shaft 轉起上嚟嗰陣有個air gap, 個leaf foil 脹開令到個Shaft 轉起嚟嗰陣掂唔到其他地方

Magnetic Bearing - 用Magnetic keep 個Shaft 响中間

https://www.youtube.com/watch?v=kQtNM72swO0

- Increase chilled water temperature, say 7^oC to 8^oC，但要考慮dehumidification問題，同埋可能會反而開冷氣開耐咗，要做個retro-commissioning先知

仲有種特別啲既Chiller 叫 Absorption Chiller，佢既特點係冇咗Compressor嗰part，用熱，尤其係廢熱取代。COP相對低，say 0.6-2

Chiller Maintenance
留定啲窿、I-Beam, Eye Bolt可以成部吊走

(Source: TheEngineeringMindset.com, EMSD BEEO)