A direct fired chiller is an absorption cooling system with an integral combustion chamber that burns natural gas, oil, or other fuels to supply the necessary heat for the absorption cycle. This configuration eliminates the need for separate boilers or steam systems, simplifying installation and reducing auxiliary equipment. Direct fired chillers deliver 50-5,000 tons of cooling capacity with thermal efficiency ratings of 0.7-0.85 COP.
Technical Details
Direct fired absorption chillers integrate burner assemblies rated from 1.5 to 15 million BTU/hour, creating a self-contained cooling solution. The units achieve chilled water temperatures of 40-45°F while maintaining outlet temperatures within 2°F accuracy. Modern direct fired designs incorporate oxygen depletion sensors and flame rollout switches meeting ANSI Z21.10.1 safety standards. Combustion efficiency typically ranges from 80-90% across operating conditions.
Applications and Practical Significance
Direct fired chillers serve locations without accessible steam infrastructure or district heating systems, including remote facilities and new construction projects. Office buildings, manufacturing plants, and healthcare facilities benefit from simplified piping requirements and reduced mechanical space demands. These systems offer excellent part-load performance with firing rates modulating between 20-100% capacity, reducing operational costs during seasonal low-demand periods compared to constant-load electric chillers.