Definition Face velocity is the approach speed of air entering the core face: face_velocity = volumetric_flow / core_face_area It is measured in metres per second (m/s). Typical range For HVAC air-to-air cores, face velocity usually sits between 1.5 and 3.5 m/s. Lower is gentler on the core and the fan; higher packs more flow into […]
Rotary Wheel Purge Sector: How Wheels Reduce Carryover
What a purge sector is A rotary energy wheel spins exhaust and supply airstreams through the same matrix, so a small amount of exhaust gas and moisture is inevitably carried into the supply. A purge sector is a slice of the wheel (typically 5-15 degrees) where a portion of the clean supply air is directed […]
Air Leakage & Cross-Contamination in Cores
Two streams, one box Every recovery device brings exhaust and supply into one casing. The question is whether they can mix. Leakage is the fraction of one stream that escapes into the other through seals, the matrix or carryover. How the technologies compare Plate (sensible): streams separated by solid walls; leakage is only through perimeter […]
Dew-Point vs Temperature Effectiveness in ERV
Temperature effectiveness (sensible) Temperature effectiveness compares supply temperature change to the maximum possible: epsilon_T = (T_supply_out – T_supply_in) / (T_exhaust_in – T_supply_in) This is the number a sensible plate reports, and it is what most generic “efficiency” labels mean. Dew-point effectiveness (total / enthalpy) For an enthalpy wheel or membrane, moisture matters, so effectiveness is […]
Fan Static Pressure Class: Matching the Fan to the Recovery Core
Static vs total pressure Total pressure is the full energy of the moving air; static pressure is the usable pushing force after velocity energy is set aside. Fans are classed by the static pressure they can develop against a system – and the recovery core is one of the biggest resistances in that system. Core […]
Liquid vs Air Cooling for Battery Storage
The Thermal-Management Shift in Grid Storage Utility-scale battery energy storage has moved from 0.5C cabinets to 1C–2C container systems of 3–5 MWh and beyond. At those power densities, keeping every cell in a tight temperature window is no longer optional — it decides cycle life, safety, and usable capacity. That is why the industry is migrating […]
Why BESS & PV Inverters Use Counter-Flow Cores
The Cooling Problem in Energy Storage and PV Inverters Battery energy storage system (BESS) cabinets and photovoltaic (PV) inverters concentrate high-power electronics – IGBT modules, DC/DC converters, reactors and capacitors – into sealed outdoor enclosures. These components dissipate heat at high flux density; if the internal air is not kept cool, semiconductor junction temperatures rise, […]
China Heat-Exchanger Manufacturing Clusters
China: The World’s Largest Heat Exchanger Producer China is the single largest producer of heat exchangers in the world, spanning plate, shell-and-tube, finned-tube, heat-pipe and air-to-air recovery units. Decades of industrial build-out, a deep supplier network and strong export competitiveness have concentrated production in a handful of regional clusters. Liaoning Changtu – the ‘China Heat […]
Variable Refrigerant Flow (VRF) Heat Recovery Systems
What Is VRF Heat Recovery Variable Refrigerant Flow (VRF) heat recovery systems use a single refrigerant loop with branch selector boxes to deliver simultaneous heating and cooling to different zones. Recovered heat from cooling zones is redirected to zones calling for heat, reducing the building net energy use. Heat Recovery vs Heat Pump VRF Two-pipe […]
Brazed Plate vs Gasketed Plate Heat Exchangers
Construction Brazed plate exchangers fuse stainless plates with copper or nickel under vacuum, with no gaskets and no frame bolts. Gasketed plate exchangers clamp plates between a fixed and moving frame using elastomer gaskets, allowing plates to be added or removed. Comparison Factor Brazed Gasketed Max temperature or pressure Higher Moderate Maintenance Sealed, service-free Plates […]