Refrigeration Capacity Load Matching

All existing refrigeration systems operate 24/7/365 and consume vast amounts of energy to maintain the required temperature to prevent spoilage of food, medicine, flowers and industrial chemicals.  It is standard practice that all refrigeration systems are designed to maintain temperature even on the hottest day (95F or higher).  Each refrigeration system consists of a condenser assembly (compressor, condenser coil and fans) and the evaporator assembly (evaporator, fans and expansion valve controller); the evaporator absorbs heat from the load and the compressor draws that heat and sends it to the condenser which discharges it to the atmosphere.  The inherent problem with this system is that the evaporator controller can only sense the load at the evaporator and has no way to pass that information to the compressor and condenser. The evaporator controller will typically see a load that is 40-80% of its full capacity while the compressor is always operating at full capacity which is a system mismatch.   This project introduces a packaged variable refrigerant flow (VRF) system with controls to safely match compressor power with evaporator loads. The benefits of VRF systems are widely accepted and the main feature is VRF systems utilize inverter-driven compressors that adjust refrigerant flow based on real-time needs. By adapting innovative VRF strategies along with new instrumentation and software algorithms to manage refrigerant flow within AC compressors, previous projects have resulted in saving 25-50% energy after retrofit. The package includes a variable frequency drive (VFD) and smart compressor control (SCC) system that continuously manages compressor speed based to match the load. The SCC senses suction and discharge temperature at the compressor and by communicating with the drive to evaluate parameters like torque and kW it safely manages speed within manufacturers’ guidelines. In addition to energy savings the SCC also protects the compressor from single phasing, unequal voltage and short cycling. It also extends compressor life via soft start and less wear.   The project will install the packaged technology on refrigeration systems that have been monitored by a remote energy monitoring platform in up to 5 locations, targeting in disadvantaged communities (DAC) that may have over 5 years of historical operating data including temperature, run times and compressor amperage. Locations may include applications in grocery stores, food processing, food wholesalers, and cold storage facilities. By leveraging existing monitoring systems and data, a solid baseline can be developed to calculate the coefficient of performance (COP) of the systems for the analysis prior to installation. After installation, the system will be monitored, and data will be collected to understand installation procedures, long-term system performance, maintenance, and operational needs. From this project, we will be able to determine cost effectiveness, safety, and best practices of each compressor retrofit. Data from this project could also be used to develop a new energy efficiency measure for CA utilities.