Page 67

Technical System Catalogue Climate Control

Sample calculation Step 1: Raise the water inlet temperature The temperature in the cold aisle is precisely definable and Qtotal (Qsens.) 80 kW (80 kW) – 79.9 kW (79.9 kW) identical throughout, thanks to optimised temperature Tair; hot (rel. humidity) 26 °C (45%) – 31 °C (32%) distribution. Tair; cold (rel. humidity) 15 °C (89%) – 19.8 °C (62.2%) Twater; inlet 10 °C – 15 °C Increasing the air intake temperature also increases Twater; return 15 °C – 20 °C the waste air temperature. Pelectr. for cold water 190 MWh/a – 139 MWh/a Increasing the air intake temperature improves the performance of free cooling. Possible energy saving in the production of chilled water: up to 26%. –26% Step 2: Reduce the volumetric air flow Qtotal (Qsens.) 79.9 kW (79.9 kW) – 88.4 kW (88.4 kW) For a constant air volume flow rate, the cooling output improves with airside temperature difference. Tair; hot (rel. humidity) 31 °C (32%) – 36 °C (25%) Tair; cold (rel. humidity) 19.8 °C (62.2%) – 19.7 °C (64.6%) By reducing the volumetric air flow, the return waste air Vair (ext. press.) 22000 m3/h (80 Pa) – 17000 m3/h (20 Pa) temperature is increased, Pelectr. for CRAC fan 3.6 kW – 1.5 kW Possible energy saving in the operation of the fans: up to 60%. –60% Step 3: Reduce the throughput The speed of the pump may be reduced because a smaller Qtotal (Qsens.) 88.4 kW (88.4 kW) – 80 kW (80 kW) amount of cooling water is required to provide the same Tair; hot (rel. humidity) 36 °C (25%) – 36 °C (25%) cooling output if the return water temperature is increased. Tair; cold (rel. humidity) 19.7 °C (64.6%) – 21.3 °C (54.2%) Twater; inlet 15 °C – 15 °C Possible energy saving in the operation of the pump: Twater; return 20.6 °C – 23.5 °C up to 14%. Vwater (Pelectr. ) 13.6 m3/h (3 kW) – 8.1 m3/h (2.3 kW) Potential saving in the production of chilled water: Pelectr. for cold water 143 MWh/a – 125 MWh/a up to 17%. –17% Summary Energy saving: Qtotal (Qsens.) 80 kW (80 kW) – 80 kW (80 kW) Tair; hot (rel. humidity) 26 °C (45%) – 36 °C (25%) Fans: 19 MWh/a Tair; cold (rel. humidity) 15 °C (89%) – 21.3 °C (54.2%) Pumps: 6 MWh/a Vair (ext. press.) 22000 m³/h (80 Pa) – 17000 m³/h (20 Pa) Cold water production: 65 MWh/a Twater; inlet 10 °C – 15 °C Overall: 90 MWh/a Twater; return 15 °C – 23.5 °C Cost saving with Rittal aisle containment: Vwater (Pelectr. ) 13.8 m3/h (3 kW) – 8.09 m3/h (2.3 kW) up to 36%. Pelectr. for CRAC fan 3.6 kW – 1.5 kW –36% Pelectr. for cold water 190 MWh/a – 125 MWh/a Pelectr. Total 248 MWh/a – 158 MWh/a Technical System Catalogue/Climate control 3 - 66


Technical System Catalogue Climate Control
To see the actual publication please follow the link above