## 3 Results and Discussion
### Analysis in an Industrial Refrigeration System
#### 3.2.2 Effects of the Interaction between the Compressor and the EC  
Simultaneous analysis of the compressor and the EC allowed us to identify that a reduction in the mass flow rate of the air of the heat exchanger was not necessarily the aim in all situations. The reduction in the mass flow rate of air in the EC can result in an increase in the power demand of the compressor due to an elevation of the condensation pressure and, consequently, of the compression ratio and compressor electricity consumption. This behavior occurs because, when the mass flow rate of air decreases with a consequent reduction in electricity demand in the EC, there is an increase in the condensation pressure of the system. As a result, the compression pressure ratio increases, and consequently, an augmentation of electrical power in the compressor is necessary to supply the new demand. Therefore, there exists a point of minimal electric current consumption by the compressor and that required by the condenser, as shown in Figure 6 for four samples that better describes this behavior. Table 3 shows the data from all measurements realized in an industrial system to verify the electric energy savings with modification of the EC mass flow rate of air. Thus, the values represent the electric power consumed by the EC and compressor. Therefore, it was possible to calculate the percentage of reduction in the overall electricity consumption in the whole refrigeration unit. Although the highest demand for electricity was related to the highest magnitudes of mass flow rate in the EC, it was not possible to define a fixed operating point for the EC fans that led to the lowest electric consumption. For the given studied conditions of the thermal load of the refrigeration system and the characteristics of the external environment where the evaporative condenser was placed, it would be necessary to modify the mass flow rate of air. The results also showed the largest difference of 11.36% for Sample 14, which indicates that for some determined conditions of the refrigeration system, the gain from the use of FHPCC can be significant. One other important aspect is that we did not find a direct relation between the magnitude of \(T_{\text{WB}}\) and the consumption of the electric power in the present investigation. For each flow rate of air investigated, a different energy consumption was verified, even with similar magnitudes of \(T_{\text{WB}}\) measured during the experiments. Additionally, for each day, the refrigeration systems operated at different conditions, e.g., the thermal load, schedule of defrost, and amount of ammonia gases that were not condensed. These  
Figure 6: Variation of electrical power of the fans’ motors of the evaporative condenser as a function of mass flow rate of air. parameters also had an influence on the energy consumption of the refrigeration system, precluding the proper definition of the influence of \(T_{\text{WB}}\) over the demanded power of the compressor and evaporative condenser. Therefore, the logical control used as its parameter the power of the system, regardless of the \(T_{\text{WB}}\) and operational conditions found during the experiments, it was possible to obtain the influence of the flow rate of air over the power of the system. To summarize, a real-time investigation in industry operation was conducted with the objective of validating the developed logical model. In the observation period, represented in Figure 7, the refrigeration system had its operation divided between the situation where the FHPCC was acting (identified as automatic control on) and simple operation without any control and considering the maximum mass flow rate of air (identified as automatic control off). Figure 7 shows the electricity consumption variations of an industrial refrigeration unit for two different conditions: (1) when the logical model (FHPCC) was in operation and (2) when the operation was suspended. When its operation was suspended, there was a clear increase in the electric energy demand.