Waste heat utilization for central heating and ventilation systems at Chassix Norway

Abstract

Chassix from south of Norway attempt to reduce their energy demand by sending waste heat to a Central Heating System, (CHS), named Case 1. The CHS heat the ventilation systems, space heat and water heating. The waste heat used is from the Sand Recycling Process, (SRP), and the Aluminum Cooling Process, (ACP). The ACP and a 600kW cooling tower are installed in May/June. Since the CHS is close to the ventilation systems using Battery Heat Exchanger, BHE, a possibility for utilizing the ventilation systems as a cooling tower, named Case 2. Case 2 is an attempt to reduce investment cost by replacing investment cost for installing the cooling tower. The potential heat recovery for CHS needed to be estimated. The estimation was based on dimension data at the building and from an Enova statistic. Estimated capacity was then compared with actual capacity from CHS. The potential heat recovery was estimated to be 1 012-1 142MWh/year, but actual data indicate that it might be lower. Case 1 is possible with reduced production at ambient temperatures above 17.5_C. With temperature above 22_C, the process needs to operate at 93%, due to possible cooling. Installing Case 1 and Case 2 are estimated as the most economically ffcient that only need 19% support from Enova to have a payback time in three years. Case 1 needs 34% support from Enova. Since the ventilation systems were 20 years old and are soon to rebuild, Chassix decided not to install Case 2.