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The escalating global energy concerns have underscored the urgent need for energy conservation, particularly within the refrigerated industry. The imperative of optimizing the performance of open refrigerated display cabinets (ORDC) has become increasingly pronounced. This study sought to investigate the impact of condensate water recycling on ORDC operations through experiment, focusing on the influence of condensate water flowrate, temperature, and heat exchanger length on key performance indicators such as thermal entrainment factor (TEF), coefficient of performance (COP), and heat transfer efficiency enhancement (η). The findings revealed that the flowrate of condensate water wielded the most substantial impact on system performance, leading to noteworthy increases of 10.42% in COP and 7.05% in η, while TEF experienced a reduction of 4.33% within a flow rate range from 0 ml/min to 54 ml/min. Notably, an optimal flowrate of 54 ml/min was identified. Conversely, the temperature of condensate water exhibited minimal influence on system performance. Increasing the length of the heat exchanger demonstrated a linear correlation with improved system performance. In practical applications, the enhancements in COP, η, and TEF, compared to scenarios without a condensate water recycling system, ranged from 2.23% to 5.80%, 1.21% to 3.68%, and 0.37% to 2.09%, respectively.

As the electric capacity of wind turbine increases, heat dissipation in pitch cabinets becomes challenging owing to the limited space and rotating conditions. To cool down the pitch cabinet more effectively and allow heat dissipation, we designed and implemented a pulsating heat pipe (PHP) in this study. We designed PHP parameters and conducted performance tests to compare the cooling performance of the fabricated PHP with that of an air-based cooling system in a 1.5 MW wind turbine. The results demonstrated steady PHP operation under rotating conditions (17.3 rpm). At a heat load of 1000 W, the evaporator outlet temperature was only 76.1 °C. However, increasing the ambient temperature adversely affected PHP operation, resulting in higher temperature and thermal resistance. The heat-pipe-based cooling system lowered the insulated gate bipolar transistor (IGBT) temperature by about 20.4 °C in relation to the air-based cooling system, while being suitable under varied conditions. Additionally, the system could successfully operate when the heat load of IGBT was 2350 W, corresponding to a 7 MW electric capacity of the wind turbine. Reducing the manufacturing cost of the heat pipe would further enhance the applicability of this system for pitch cabinet IGBT cooling, such as decreasing payback period.

In this study, we analyzed the relationship between the refrigerant distribution of a multiparallel evaporator and the structural design of a distributor to address uneven distribution of gas–liquid refrigerants in multiparallel evaporators under variable operating conditions. Herein, we proposed the shunting concept of “flow pattern setting and critical distribution” and designed a theoretical model for a rectifying nozzle-type critical distributor (RNCD). We built the experimental bench of a multiparallel evaporator using an RNCD and compared the cooling time of each cold storage, the superheat of each branch pipe, the cooling capacity of each cold storage, and the pressure drop of the distributor. Further, we investigated the shunting performance of the RNCD. The experimental results showed that the evaporation temperatures were −32 °C to −24 °C when cold storage temperatures of −22 °C to −14 °C, respectively. The unevenness of superheat at the outlet of each evaporator branch pipe of the RNCD was 0.0884–0.1275, while the unevenness associated with the refrigeration capacity of each cold storage was 0.1424–0.1714. This study provides basic research information to solve the problem of uneven refrigerant distribution when considering gas–liquid two-phase flow in multiparallel evaporators under variable operating conditions.