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In a liquid desiccant air conditioning system the regenerator is one of the essential components. The effectiveness of the regenerator directly influences the system performance. An experimental investigation on the performance of packed tower for regeneration of liquid desiccant is carried out. The experimental test unit has been designed and installed in the combustion Lab., Faculty of Engineering, Mansoura University, Egypt. A solution of calcium chloride is used as a working desiccant with a packing of burned clay pieces with a random shape, its porosity is about 0.22 and the average size and weight of the piece are about (90.25 cm3, 88.4 gram) respectively. The input variables used in the experiment are air inlet temperature, air flow rate and solution flow rate. The outlet parameters which are measured or calculated from the experimental results are air outlet temperature, air humidity ratio, desiccant solution outlet temperature and concentration. To illustrate the effect of air and liquid desiccant parameters on the outlet variables the experimental results are plotted. Based on these results, higher air inlet temperature (Tai = 60, 80, 100 and 120 °C) where the air inlet humidity ratio (0.0127, 0.0123, 0.0114 and 0.0130 kg/kgda) results in higher average air humidity ratio (0.0206, 0.0232, 0.0249 and 0.0334 kg/kgda) and the %age change of desiccant solution concentration (0.63, 1.13, 1.95 and 2.25 %) respectively. And higher air flow rate (Ma = 0.0252, 0.0529, 0.0659 and 0.0683 m3/s) where the air inlet humidity ratio (0.0147, 0.0177, 0.0178 and 0.0184 kg/kgda) results in higher average air humidity ratio (0.0245, 0.0293, 0.0302 and 0.0312 kg/kgda) and the %age change of desiccant solution concentration (0.78, 2.21, 2.57 and 3.01 %) respectively. Increase in solution flow rate (Ms = 1, 2 and 3 LPM) where the air inlet humidity ratio (0.0175, 0.0151 and 0.0148 kg/kgda) results in lower average air humidity ratio (0.0278, 0.0274 and 0.0267 kg/kgda) and the %age change of desiccant solution concentration (2.86, 2.58 and 2.23 %) respectively.

In this paper, the effects of constant, alternating and rotating magnetic fields on the laminar forced convective heat transfer of /water nanofluid (ferrofluid) in a uniformly heated copper tube are investigated experimentally. The local convective heat transfer coefficients are measured in the hydrodynamically fully developed region. The experiments are conducted using ferrofluid with 2.5% mass concentration. A quadrupole magnetic field system has been designed and constructed to generate the constant, alternating and rotating magnetic fields. For the magnetic field system, different operation modes were also examined and the most efficient mode was obtained. The effects of alternating magnetic field frequency and rotating magnetic field speed were also studied. The primary experiments showed that Uni-pole magnetic field system provides the maximum heat transfer enhancement. A significant enhancement in the local convective heat transfer of ferrofluid was observed by application of constant magnetic field. It was observed that constant magnetic field has provided a maximum local heat transfer enhancement of 119.6% compared to the case without magnetic field for ferrofluid with 2.5% mass concentration and at Re = 2000. This value is decreased to 106.7% and 96.8% by application of rotating and alternating magnetic field, respectively. Additionally, increasing the alternating magnetic field frequency and the rotating magnetic field speed adversely affect the heat transfer enhancement.