Website Glossary

Thermal Management System

Active Cooling Loop
Thermal loop that consists of a refrigerant circuit containing a scroll compressor, chiller, expansion vale, and condenser to maintain coolant temperatures when the ambient air temperature is close to or above the target coolant temperature.

Active Heating Loop
Thermal loop containing a high voltage (HV) electric heater to warm the coolant to the desired set point, typically to pre-condition the battery or passenger heating loop.

Aluminum Tank E-Fan Cooling Module (AT-ECM)
Consists of a thermal management passive cooling loop for diesel, CNG, or hybrid electric vehicles to limit engine temperature and prevent overheating.

Battery Pre-Conditioning
Warming up the battery packs within their optimal temperature range before the vehicle can be charged or driven.

Battery Thermal Management System (BTMS)
Thermal Management system designed to regulate battery temperatures in all ambient temperatures. Containing three thermal loops: active cooling, passive cooling, and active heating, a battery thermal management system is equipped to optimize battery temperatures to support performance, range and longevity.

Electronics Cooling Package (ECP)
Consists of a thermal management passive cooling loop designed to maintain derating temperature ranges for inverters, converters, traction motors, onboard chargers and other electronics

EV Cooling System
Thermal management system for electric vehicles, typically containing active and passive cooling loops.

A programmed default mode into smart electric component firmware that protects the device being controlled in the event of signal failure or signals outside of a set range.

Fuel Cell Stack Cooling Package (FC-SCP)
Thermal management passive cooling module that regulates fuel cell stack coolant temperatures to help ensure optimal performance of the fuel cell.

Passive Cooling Loop
An energy efficient thermal loop containing a radiator and an array of smart electric fans that is designed to reject heat from the coolant loop to ambient air.

Predictive Cooling
Firmware with an intelligent algorithm that monitors coolant temperatures and communicates to the thermal system when to actively manage cooling and minimize temperature swings.

Waste Heat Recovery (WHR)
The recovery of waste heat from one system where it is not required (for example. from an item that needs to be cooled) to another where it can do useful work (for example, cabin heating).  The recovery is typically done by means of two coolant loops passing through a heat exchanger.


Air-Cooled Condenser
A heat exchanger that condenses high-pressure refrigerant vapor into a liquid by transferring heat from a refrigerant circuit to air.

Charge Air Cooler
A heat exchanger used to cool engine intake air to increase its density.

A liquid cooled heat exchanger that evaporates liquid refrigerant to vapor by transferring heat from a liquid circuit to refrigerant circuit.

Expansion Valve (EXV)
The expansion valve removes pressure from the liquid refrigerant to allow expansion or change of state from a liquid to a vapor in the evaporator

Flux-Free Heat Exchanger
A Brazed heat exchanger without the use of flux. Typically required in fuel cell and low conductivity fluid applications.

Heat Exchanger
Heavy-duty metallic component designed to transfer heat between a source and a working fluid.

Liquid-Cooled Condenser (L-CON)
A heat exchanger that condenses high-pressure refrigerant vapor into a liquid by transferring heat from a refrigerant circuit to a liquid coolant circuit.

PTC Heaters
Positive Temperature Coefficient (PTC) heaters add heat to a coolant circuit, with their power output falling in proportion to the coolant temperature. This is a achieved by the electrical resistance of the heating elements rising significantly with the temperature.

Scroll Compressor
A smart electrically-driven component that compresses the refrigerant in the refrigerant loop. The scroll compressor uses two interleaving scrolls to pump the refrigerant.

Smart Electric Product
Components with integrated firmware that are able to communicate with the thermal management system’s controllers and vehicle ECUs.

Thin-Film-Based Heaters
A means of adding heat to a coolant circuit through a complex layer system of heating elements securely and directly bond to a heat-exchanging element that is indirect contact with its medium. This design enables nearly loss-free and rapid conversion of electrical power into heat, for a high degree of efficiency and control.

Vehicle Systems

Battery Management System
A mechanism that transfers heat to and from the battery cells with coolant either through direct immersion or conduction through a battery cooling plate or other structure.

Controller Area Network Bus is a communications protocol used by heavy-duty vehicles that enables communication  between microcontrollers and devices connected to the bus.

A device that converts one DC voltage level to another.

DM 1
Diagnostic Messages 1 (DM1) are part of SAE J1939 diagnostic messaging protocol defined in J1939-73 and serve as a comprehensive means of conveying diagnostic information. These messages primarily focus on active fault codes, which indicate current issues or malfunctions within the vehicle’s systems. DM1 messages are broadcasted by the source ECU to the entire network and can be received and processed by other ECUs.

DM 2
While DM1 messages focus on active fault codes, DM2 messages are used to communicate previously active or historical fault codes. These codes have been resolved or are no longer active but are retained in the ECU’s memory for diagnostic purposes. DM2 messages also include information about cleared faults, aiding technicians in understanding the vehicle’s history and providing insights into recurring issues.

Electronic Control Unit (ECU)
An embedded systems in vehicular electronics that control one or more of the electrical systems or subsystems in the vehicle.

A program for hardware devices that determines how they operate and communicate with other devices.

Hydrogen Combustion Engines
Propulsion system that directly burns hydrogen through a combustion process.

Hydrogen Fuel Cell
A device to convert hydrogen gas into electricity through an electrochemical reaction with oxygen that emits water vapor as a waste product.

Internal Combustion Engine, typically using diesel, CNG, hydrogen, or gasoline as its energy source that can propel a vehicle

A device that converts voltage between DC and AC.

A set of recommended practices defined by the Society of Automotive Engineers for communication and diagnostics among vehicle components.. J1939 provides a higher layer protocol that includes CANBUS, offering a standardized method of communication across electronic control units across manufacturers.

On board charger (OBC)
A device for converting alternating current (AC) power from an AC source (for example, a electricity grid) to the direct current (DC) needed to charge a vehicle’s battery pack.

RP1210 Adapters
An electrical adaptor used for reprogramming and analyzing Electronic Control Units (ECUs) and accessing diagnostic interfaces in heavy-duty vehicles.

Traction Motor
An electric motor used in heavy-duty electric vehicle propulsion.

Vehicle Control Unit (VCU) or Master Controller
Primary controller in a cascade control system that communicates and gives orders to secondary controllers via remote setpoint signal.