Performance assessment of hybrid desiccant cooling system at various climates
In our work, operation of hybrid desiccant cooling system (HDCS) has been investigated based on experimental studies. Different climates have been created by changing the temperature and humidity of HDCS inlet air, using an electrical heater and a centrifuge humidifier. Input energies, temperature of various points, and their relative humidity have been measured at the created climates. Coefficient of performance (COP), thermal coefficient of performance, and electrical coefficient of performance (ECOP) of the HDCS have been calculated. As a reference situation, vapor compression system (VCS) was examined at the same condition as HDCS. Results show that COP of HDCS in comparison with VCS decreased about 36% and 28% in hot-dry and hot-humid climates, respectively, which is due to the thermal energy consumption in HDCS. In contrast its ECOP increased, which means that by using HDCS some electrical energy would be saved. Defining operating cost index (OCI) parameter, operation costs of VCS and HDCS have been compared. Analyzing the OCI results shows that in HDCS, although decreasing the electricity consumption results in more usage of natural gas, these systems are economical especially in those countries with low natural gas prices.
Studies on solid desiccant based hybrid air-conditioning systems
Abstract Desiccant based air-conditioning systems offer a promising alternative to conventional air-conditioning systems using vapour compression refrigeration especially under conditions involving high latent loads. The desiccant can be used either in a stand-alone system or coupled judiciously with a vapour compression system to achieve high performance over a wide range of operating conditions. In this paper, the results of a detailed study of solid desiccant-based hybrid air-conditioning systems are presented. The literature review revealed that various authors differ in their evaluation of the efficacy of these systems. This seems to be due to different methods of modelling of dehumidifier and differences in the operating conditions of the cycles employed. Accordingly, the performance of four hybrid cycles (which include a new proposed cycle) for typical hot-dry and hot-humid weather conditions has been evaluated using a detailed procedure for the analysis of rotary dehumidifier, the most commonly employed industrial dehumidifier, based on the analogy method of Maclaine-Cross and Banks [I.L. Maclaine-Cross, P.J. Banks, Coupled heat and mass transfer in regenerators — predictions using an analogy with heat transfer, Int. J. of Heat and Mass Transfer 15 (1972) 1225–1241]. Effect of room sensible heat factor, ventilation mixing ratio, and regeneration temperature has also been studied. The results show that solid desiccant-based hybrid air-conditioning systems can give substantial energy savings as compared to conventional vapour compression refrigeration based air-conditioning systems in most commonly encountered situations.
Portable Computing in Psychiatry
Personal digital assistants (PDAs) or handheld computers have become more popular in the practice of medicine. These devices have implications for psychiatric practice, and this paper reviews various published articles describing their use. The literature demonstrates their use in document editing, patient tracking, accessing medical information and drug reference guides, prescription writing, and medical education. Security on these devices is covered, and the value and increasing implementation of PDAs in psychiatry is discussed.