MRBraz to install six more low-charge ammonia AC chillers in 2019

MRBraz & Associates, a supplier of industrial refrigeration and air-conditioning (AC) equipment, said that in 2019 it will install low-charge packaged ammonia/glycol DX chillers providing AC for offices at six warehouses operated a major U.S. retailer.

The company has previously supplied this AC chiller to 10 of the retailer’s warehouses since 2012. “As [the retailer] sees an ROI, they are putting in more in 2019,” said Daniel Braz, vice president of operations for MRBraz. (He declined to name the retailer without their permission.) The AC chillers are replacement units for R22 systems using 180-220 lbs of refrigerant.

Braz spoke about the AC units at the IIAR Natural Refrigeration Conference & Expo, held in Phoenix March 4-6. In 2017, MRBraz displayed the AC unit at the IIAR Conference in San Antonio, Texas.

MRBraz also has two more [low-charge AC chillers] in the manufacturing stage that will be installed the following fiscal year at the retailer’s warehouses. “One is in California, and we’re excited to see how it goes there,” he said, pointing out the new HFC-reduction legislation the state is implementing.

In addition, MRBraz is working with a school district in Houston, Texas, on a plan for a new high school that would use the AC units rather than a synthetic-refrigerant system. A mobile trailer unit is also available.

Low-charge ammonia AC chillers are relatively rare in the U.S. “It’s gaining ground, but it takes time to cultivate it and show it works,” Braz said. “But legislation and technology are making a fertile ground for natural refrigerant to come into the HVAC space.”

Campbell Soup uses a similar AC chiller from Azane at a facility in Napoleon, Ohio.

MRBraz’s skid-mounted AC chiller, stationed in a parking lot outside the retailer’s warehouse, is designed with only about 1 lb/TR of ammonia, which is confined to the unit; it pumps a chilled glycol solution as a secondary coolant to an air handling unit, which delivers cool air to the office space.

The typical chiller contains about 100 lbs. of ammonia for 100 TR of capacity cooling 25,000 sq ft of space; it employs a VFD screw compressor, ECM fan motors an air-cooled condenser, food grade oil, and an ammonia/glycol heat exchanger with a temperature approach of only 3°F-5°F. The units, available in capacities ranging from 30-110 TR, require a single 180-V power feed.

Braz presented data showing the efficiency benefits of the AC units. He pointed out that ammonia has a lower HP/TR (1.3) than R22 (1.5) and HFCs like R410A (1.7) and R134a (1.5).  In one example, the MRBraz AC chiller uses 1.99 HP/TR compared to 2.15 HP/TR for a pre-existing R22 chiller; the COP’s were 2.37 and 2.20, respectively. In its first year of operation, the low-charge chiller saved the warehouse about $100,000, which produced a “healthy ROI,” said Braz.

MRBraz handles the manufacturing, installation and maintenance of the units – from “cradle to grave,” said Braz. It also does performance monitoring for preventive maintenance.

To enhance the safety of the AC units, leaked ammonia is dispersed vertically by fans several hundred ft into the air “where it is not harmful,” said Braz. Permits to use the units have been obtained without difficulty from local municipalities, he added.

The company reports no complaints about ammonia leaks in the retailer's parking lots.