The Effect of Microencapsulated PCM Slurry Coolant on the Efficiency of a Shell and Tube Heat Exchanger

Abstract

This paper describes the results of experimental studies on heat transfer in a shell and tube heat exchanger during the phase changes of the HFE 7000 refrigerant. The studies were performed using a mixture of water and a microencapsulated phase change material as a coolant. HFE 7000 refrigerant condenses on the external surface of the copper tube, while a mixture of water and phase change materials flows through the channels as coolant. Currently, there is a lack of research describing cooling using phase change materials in heat exchangers. There are a number of publications describing the heat exchange in heat exchangers during phase changes under air or water cooling. Therefore, the research hypothesis was adopted that the use of mixed water and microencapsulated material as a heat transfer fluid would increase the heat capacity and contribute to the enhancement of the heat exchange in the heat exchanger. This will enable an increase in the total heat transfer coefficient and the heat efficiency of the exchanger. Experimental studies describe the process of heat transfer intensification in the above conditions by using the phase transformation of the cooling medium melting. The test results were compared with the results of an experiment in which pure water was used as the reference liquid. The research was carried out in a wide range of refrigerant and coolant parameters: ṁr = 0.0014–0.0015 kg·s−1, ṁc = 0.014–0.016 kg·s−1, refrigerant saturation temperature Ts = 55–60 °C, coolant temperature at the inlet Tcin = 20–32 °C, and heat flux density q = 7000–7450 W·m−1. The obtained results confirmed the research hypothesis. There was an average of a 13% increase in the coolant heat transfer coefficient, and the peak increase in αc was over 24%. The average value of the heat transfer coefficient k increased by 5%, and the highest increases in the value of k were noted at Tin = 27 °C and amounted to 9% in relation to the reference liquid.

New environmentally friendly low-pressurere frigerants mini-channel

“…The tests were carried out under the following conditions: mass flux of refrigerant m r = 0.0014-0.0015 kg/s, mass flux coolant m c = 0.014−0.016 kg/s, refrigerant saturation temperature t s = 55−60 • C, inlet coolant temperature t cin = 20−32 • C, and heat flux density q = 7000−7450 W/m 2 . The average increase in the heat transfer coefficient was 13% [40]. Woodoc et al [41], on the other hand, investigated the use of the HFE7000 refrigerant in an 800-µm-thick silicon mini-heat exchanger (MECH-X).…”

Innovative approaches and modified criteria to improve a thermodynamic efficiency of trigeneration plants

“…Different heat exchangers might be used to intensify heat transfer [17,18] in utilizing [19,20] and heat transforming contours [21,22]. Besides, special jet devices [23,24], using high pressure potential, can be applied for circulation of working fluids such as ejectors and thermopressors [25,26] in stationary and transport applications [27,28].…”

A novel degree-hour method for rational design loading

“…In order to increase heat flux at reduced temperature difference in heat exchangers, leading to decrease the sizes of heat exchangers and corresponding energy spent to cover their aerodynamic resistance at lowered leaving temperature of cooled air simultaneously, the various methods of heat transfer intensification 47,48 and advanced heat exchangers 47,49,50 and injector circulation contours 10 are proposed.…”

“…In order to enhance and estimate the efficiency of fuel saving technologies based on engine cyclic air cooling the various simulation methods with using ANSYS program complexes, 49,51 methods for processing the data on ambient air parameter influence on AECS loading, 52,53 air temperature and humidity control, 54,55 exhaust energy recovery 56 and economical analysis 57 were applied.…”

“…The latter, in its turn, enables deeper air cooling by applying, for instance, the coolants of different temperature (chilled water, boiling refrigerant) in two-stage hybrid air coolers 35,46 fed by coolants from WHRCh of combined types, for instance absorption-ejector chillers (AECh). 10 In order to increase heat flux at reduced temperature difference in heat exchangers, leading to decrease the sizes of heat exchangers and corresponding energy spent to cover their aerodynamic resistance at lowered leaving temperature of cooled air simultaneously, the various methods of heat transfer intensification 47,48 and advanced heat exchangers 47,49,50 and injector circulation contours 10 are proposed.…”