Industrial Heat Pumps
Industrial heat pumps are a side branch of refrigeration system technology. In a typical refrigeration system the emphasis is on cooling only. This cooling is accomplished by transferring heat from one area to another. As is the case with refrigeration systems, this transferred heat is almost always wasted. The only benefit is the cooling effect produced.
However, a refrigeration system can also be utilized for heating purposes. Used in this manner, the primary duty of the refrigeration system is to transfer this energy to a higher temperature suitable for heating purposes. In this instance, heat is the desired product, not cold.
Combining simultaneous cooling and heating processes can provide significant benefits. An industrial heat pump can provide these two separate utilities (heating and cooling) for a wide range of operating conditions. The diagram shows an example of this. The cooling effect created by the heat pump evaporator plus the energy consumed (work) is transferred to the heat pump condenser for heating.
A typical refrigeration system rejects heat to the atmosphere. However, an industrial heat pump amplifies this heat energy for further use. The industrial heat pump simply transforms low heat grade energy to a useful temperature instead of wasting the heat. As a result, the heat pump can provide significant energy savings when passive heat recovery devices are not adequate.
Industrial heat pumps must be applied on two principles if they are to be successful installations. To provide sufficient process heating capability it is necessary to consider:
- The total heat energy input (Btu per hour or kW), and
- The temperature ( °F or °C) at which the energy is required
Long periods of continuous operation are especially advantageous for industrial heat pumps applications. The economics of use improve when the heat pumps operate in these conditions. In other words, the more you use an industrial heat pump, the more cost-effective it becomes.
A common approach for measuring the efficiency of an industrial heat pump is based on the concept of COP (Coefficient of Performance). This is shown below in simple form.
In all cases, a closed cycle heat pump will have a COP greater than 1. This simply states any energy recovered and amplified to a higher temperature (by a heat pump) will always be more efficient, than a fossil fuel source meeting the same equivalent heating requirement.
Temperatures approaching 212 °F (100 °C) or higher can be produced by an industrial heat pump. Instead of recovering heat energy at low temperatures, an industrial heat pump transforms the energy into a suitable temperature for reuse in the process. The specific limits on temperature are determined by the equipment design envelopes and refrigerant utilized in the heat pump.
Another important concept in this regard is that of thermal lift. Thermal lift is the difference in temperature between the energy input source and the final required temperature at the energy output.
As the thermal lift increases, more input power is required for the heat pump. While heat pumps do consume energy they do so at high COP’s. This provides leverage in reducing the use of fossil fuel ... and the cost per unit of heat energy delivered.
The emissions of carbon dioxide (CO2) released as a by product of combustion processes are also reduced when fossil fuel use is curtailed. This is especially useful for those facilities investigating the issues of sustainability and environmental corporate awareness.
The use of industrial heat pumps can offer significant benefits in addition to the economic value of lower energy use. The application of these should be considered when relatively low temperature heating (<250 °F or 121.1 °C) is required.
Give us a call to find out how we can help you apply these principles to your operations for greater energy cost savings!