Per-Facility Analysis · Updated July 27, 2026

24MW Chicago Market Data Center: Waterless Dry Cooler Recirculation Exterior CFD Case Study

A waterless, dry-cooled campus, and a symmetric recirculation risk. Public-source inputs. Screening-level.

Waterless cooling architecture makes exterior intake air quality a first-order design concern. Without evaporative assist, any recirculation that raises dry-cooler intake temperature translates directly into lost capacity. If you are developing or operating a waterless or low-water data center, we'd like to talk to you early in your design process. Resolved Analytics provides independent exterior thermal risk analysis for owners and developers who want this picture before construction.

What This Page Covers

This page presents a screening-level exterior CFD analysis of a 24 MW data center in the Chicago market. The facility's defining feature within the survey cohort is its cooling architecture: it is waterless. Heat is rejected by rooftop dry coolers on a closed-loop glycol circuit, which means no cooling towers, no evaporative loop, no water consumed for cooling. That makes this facility a clean comparison point to the cohort's conventional chiller-and-tower facilities and to its pumped-refrigerant facilities.

The analysis examines a single, deliberately chosen worst-case wind condition and the recirculation behavior it produces between the ground-level generators and the rooftop dry-cooler intakes.

Facility Context

The facts below are derived entirely from cited public sources including the operator's published specifications, press coverage, public facility databases, and aerial imagery. No proprietary drawings, specifications, or operational data are used.

Address: Chicago market.

Owner-operator: A major Chicago-market colocation operator. Facility operational February 2025.

Critical IT capacity: 24 MW, N+1 redundancy, two-story purpose-built campus.

Cooling: Waterless. Rooftop dry coolers (closed-loop glycol, air-cooled), arranged in two arrays: one on the northeast side, one on the southwest. Side-draw intakes through V-coil faces; vertical discharge. No cooling towers, no water consumed.

Backup power: Ground-level generator enclosures, split into a northeast group and a southwest group, on concrete pads. Stack exhaust.

Site layout: Symmetric about the building's long axis: generators and dry coolers appear on both the northeast and southwest sides. This symmetry is central to the result below.

Electrical service: 138 kV transmission to 34.5 kV building distribution.

Scenario Presented

Wind and ambient.
Wind from the northeast (45°) at 10 mph, 98°F ambient. The northeasterly direction is the case that drives the northeast-side generator exhaust toward the rooftop dry-cooler intakes.

Operating scenario.
All generators and all rooftop dry coolers running at full load, which is the on-generator condition that maximizes both the exhaust source and the heat-rejection demand simultaneously.

This page presents the northeasterly case. Additional wind directions were examined as part of the survey's directional screening and are available to the engineer of record on request, including, by the symmetry of the site, the mirror-image southwesterly condition discussed below.

What the Model Shows

The observations below are qualitative readings of the presented scenario. Quantitative outputs (per-unit intake temperatures, recirculation magnitudes) are shared with the engineer of record on request.

1. Generator exhaust impinges on the rooftop dry coolers. Under the northeasterly wind, flow patterns develop that carry exhaust from the ground-level generators up onto the rooftop dry-cooler array, a condition that can raise dry-cooler intake temperatures past the ~120°F regime where shutdown setpoints engage. Because the units reject heat sensibly to ambient air, intake-air temperature is exactly the variable that governs their capacity.

2. The risk is symmetric. The site places generators and dry coolers on both the northeast and southwest sides. The same mechanism that the northeasterly wind drives on one side, a southwesterly wind drives on the other. A study that only ran one prevailing direction would characterize half the building and miss the mirror-image exposure entirely.

3. Waterless cooling raises the stakes on intake air. With no evaporative assist, a dry cooler's heat-rejection capacity is tied directly to the dry-bulb temperature of the air it draws in. Any exhaust recirculation that warms that intake air translates more directly into lost capacity than it would for an evaporatively-assisted system, making exterior intake-air quality a first-order design concern for this architecture.

4. Building and equipment geometry govern the result. Whether the ground-level exhaust reaches the roofline, and which units it lands on, is a function of building height, generator placement, and dry-cooler array position. This is a campus-geometry question that only an exterior model resolves.

Methodology

The methodology applied here is the same standardized exterior CFD approach applied to every facility in the cohort: cylindrical far-field domain, logarithmic atmospheric boundary layer inlet, polyhedral mesh in Siemens STAR-CCM+, realizable k-ε RANS baseline. The presented case uses a 98°F ambient, near the Chicago-area summer design condition (site elevation ~735 ft). Full domain setup, boundary conditions, solver choices, and stated limitations are documented at the Methodology page. Key terms used here are defined at the Key Terms and FAQ.

For the Engineer of Record

The full per-facility figure set, the complete wind-case matrix (including the symmetric southwesterly condition), and a quantitative summary are available on request. We share these directly with the named engineer of record, not with building owners, operators, or other parties. Because dry-cooler capacity is governed directly by intake-air temperature, the exterior recirculation picture is of particular relevance to a waterless architecture. Contact stewart@resolvedanalytics.com and reference this Chicago facility.

About the Author

Stewart Bible, Principal, Resolved Analytics. Resolved Analytics is a Computational Fluid Dynamics consulting practice and authorized Siemens STAR-CCM+ reseller, with a long-standing service line in mission-critical facility exterior analysis. Contact: stewart@resolvedanalytics.com.

Disclosure

This is independent research conducted by Resolved Analytics without engagement, sponsorship, or input from the building owner, operator, or engineer of record. All inputs are derived from cited public sources; no proprietary drawings, specifications, or operational data are used. Results represent idealized exterior conditions and do not represent the actual as-built performance of any facility. No claims are made regarding life-safety, code compliance, or operational performance. All firm and project references have been anonymized. This material is not engineering services rendered to any party.