Challenge
A multinational food producer with a large plant in France has been exploring ways to dramatically reduce energy consumption using Trane high efficiency equipment. Both cooling and heating are required during the company’s manufacturing process – 370 kW of cooling capacity and 540 kW of heating.
The company wanted to end its dependence on gas-powered boilers for heating and achieve energy savings of 60% through heat recovery. The goal was to recover and recycle waste heat generated during the cooling process. There was an additional requirement for the solution to comply with low acoustic levels as well as reduce the carbon footprint of HFC refrigerant.
Solution
Following an energy audit, the company identified ways to optimize the process. The first proposal was based on the recovery of heat evacuated during the cooling operation. The company was already using four Trane RTUD chillers and was hoping to secure heat recovery using these existing units. However, the pressure drop meant this wasn’t possible.
Instead, Trane France worked closely with the contractor to devise another technical solution. This involved replacing one of the RTUD units and the tube-in-shell exchanger with:
• 1 x XStream™ RTWF G 155 water-to-water heat pump and
• 1 x dry cooler.
A plate heat exchanger was installed upstream of the air condenser where the hot water return was heated before storing it in a water tank.
Results
The new heat pump uses R1234ze refrigerant which has near-zero GWP. In tandem with the heat exchanger, it produces the equivalent of 500 kW of hot water which is sufficient to cover the factory’s entire process heating requirement. The air condenser also allows any remaining heat to be dissipated into the outside air if necessary. One of the factory’s two gas boilers has been kept as a backup but hasn’t been needed to date.
In addition to heat recovery, the unit controller has also been modified. Variable speed drives have been installed and the three-way valves replaced by two-way models to improve energy distribution in the system.
Savings far exceed the original goal of 60%. The company is delighted that, after two years of operation, there has been an 80% reduction in energy consumption.
The solution also satisfies the need to keep sound levels to a minimum and has reduced the site carbon footprint with zero ODP and under one GWP refrigerant R1234ze.
Following the success of the project, Trane France has carried out a further sustainability and performance enhancement project with the customer at another factory.
