ZEERS
By integrating a heat pump/chiller in the Zero Emission Energy Recovery System (ZEERS), not only can system efficiency be further increased, but fossil fuels can be completely eliminated for heating and cooling the supply air.
AVOIDANCE OF FOSSIL ENERGY SOURCES THROUGH ZEERS
Even highly efficient energy recovery systems are rarely able to achieve the setpoint temperature at all operating points without supplemental energy. With highly efficient systems, the external energy sources can be minimal.
REQUIREMENTS AND SUSTAINABILITY
The external energy sources can be classic gas boilers, heat pumps or even district heating sources. The energy is added to the water/glycol circuit using plate heat exchangers. However, a precise analysis of the options and the corresponding costs are crucial for an effective design. With current sustainability practices, the use of fossil fuels is becoming less desirable. The use of geothermal probes is often costly, or, depending on zoning restrictions, not possible. The availability and costs of district heating connections must also be carefully considered.
With the Zero Emission Energy Recovery System (ZEERS), Konvekta offers the possibility of increasing the energy yield to supply the remaining energy demand electrically without the use of fossil fuels.
INNOVATIVE ZEERS CONCEPT
This is made possible by combining the high-performance ERS with a heat pump that feeds the required heat and cold into the water/glycol cycle using a plate exchanger. The heat pump/chiller is fed by an additional source/sink heat exchanger, which is used downstream of the heat exchanger of the ERS in the exhaust air.
SUMMER OPERATION OF A ZEERS
In summer, the second exhaust air coil is used for heat rejection for the chiller. This enables the chiller to feed the required cold into the water/glycol circuit using a plate heat exchanger on the evaporator side. An efficiency-increasing effect is achieved if the air before the second exhaust coil is adiabatically cooled.
WINTER OPERATION OF A ZEERS
In winter operation, the ZEERS circuit is switched over. The second exhaust air heat exchanger is used as the heat pump’s energy source. This enables the heat pump to feed the required heat using a plate heat exchanger into the water/glycol circuit. Since the ERS already extracts heat from the exhaust air efficiently, further energy recovery at low outside temperatures is only possible by the targeted freezing of the exhaust air heat exchangers and by the automatic defrosting process achieved by the Konvekta Controller. The control system deliberately allows a controlled undershooting of the dew point in the exhaust to be able to use this residual energy.
DATA-BASED DESIGN AND CONTROL
As with all other applications of Konvekta ERS, ZEERS is also designed with the Syskon tool according to the concept of the Digital Twin. The overall system is optimized for all conditions over the 8760 hours of the year for the respective location. The exact performance and energy values for ZEERS are known in the design phase and can be used for investment analysis.
EFFICIENCY INDICATORS
Energy recovery systems that include an integrated heat pump, like ZEERS, do not fall within the scope of EU (VO) 1253/2012, and simply calculating the heat recovery coefficient over the entire system is misleading because the heat pump consumes electrical energy. In addition, energy efficiency calculations in which the consumption of electrical energy was taken into account, are only reference values since they were determined for a specific operating point. These values do not reflect the system efficiency in the annual cycle, since the COP/EER, the efficiency of the heat pump/chiller, is not a constant value. This varies depending on the current operating point. Using Konvekta’s data-analytical approach, the net energy recovery over the entire annual cycle is determined for ZEERS in each case by considering the variable electrical energy demand of the heat pump/chiller. The data also allows a reliable return on investment and investment analysis to be carried out for a ZEERS design.
