Central air conditioning systems are employed to regulate air quality to an ideal level. Nevertheless, these systems can consume a significant quantity of energ Central air conditioning systems are employed to regulate air quality to an ideal level. Nevertheless, these systems can consume a significant quantity of energ

Rather than cooling an entire facility, local area cooling—achieved by placing simple-shaped heat exchangers near plants—could be an effective, low-energy climate regulation strategy for agricultural fields in greenhouses. In this study, a comparative analysis was performed for three serpentine-shaped heat exchangers varying in pipe diameter (12.7 and 15.88 mm) and pipe spacing (50 and 100 mm). Their heat transfer performance and air temperature distribution were measured in terms of local area cooling. Local air temperatures below the heat exchanger were also measured, whereas temperatures above the unit served as a reference. Both heat transfer performance and the pressure drop in the heat exchangers were investigated as well. Cooling experiments were conducted with inlet fluid temperatures from −5 to 10 °C and flow rates from 0.3 to 3.0 L/min (Re = 50–1394). The results showed that local air temperature reductions reached approximately 9 °C for the 12.7 mm pipe with 50 mm spacing, 10 °C for the 15.88 mm pipe with 50 mm spacing, and 5 °C for the 15.88 mm pipe with 100 mm spacing. Heat flux for the 15.88 mm pipe was two-thirds lower at a spacing of 50 mm and 1.5 times higher at a spacing of 100 mm compared to the pipes smaller in diameter. Moreover, pressure drops for the large-diameter pipes were about half those of the smaller pipes. The results from this experimental study are expected to contribute to practical greenhouse cooling applications and provide useful guidance for configuration selection for heat exchangers.

SMEs in Thailand use simple paper-based logbooks to record operating data of their equipment and processes such as pressure, temperature, and mass flow rate. Ho SMEs in Thailand use simple paper-based logbooks to record operating data of their equipment and processes such as pressure, temperature, and mass flow rate. Ho

This study investigates the performance of unit-element heat exchangers. Particularly, it focuses on the characteristics of the local air temperature profiles and heat transfer performance of serpentine copper pipe heat exchangers with different diameters, aiming to identify an effective configuration for greenhouse crop cultivation. The term local air temperature refers to the air temperature near the cultivational crops. Cooling experiments were carried out using serpentine heat exchangers with outer pipe diameters of 12.7 mm and 15.88 mm under varying inlet fluid temperatures (−5 °C to 10 °C) and fluid flow rates (0.3–3.0 L/min). Measurements included local air temperature, inlet and outlet fluid temperatures, pipe surface temperatures, and pressure drop, while relative humidity was monitored by checking water condensation on pipe surfaces. The results showed that the average reduction in local air temperature in the area below the heat exchangers reached up to 9.0 °C for the 12.7 mm diameter pipe and 10 °C for the 15.88 mm diameter pipe. Moreover, the pressure drop with the 15.88 mm exchanger was about half that of the 12.7 mm exchanger. These findings highlight the advantages and disadvantages of each type of heat exchanger. Furthermore, they will be useful in selecting an appropriate heat exchanger for greenhouse farming.