Two evaporative-cooling materials were studied which are (i) salt hydrates and (ii) polyacrylic acid for the purpose showing proof of concept of being able to put evaporative-cooling materials into a composite with the Air Force polyimide AFR-PEPAN. The salt hydrates were observed to absorb water and then evaporate water, but due to having a collapsible lattice, made them incapable of reabsorbing water. Polyacrylic acid was mixed into an epoxy sheet at polacrylic acid weight percentages of 5, 10, 12.5. For each weight percentage there was a hydrated epoxy specimen and a dry epoxy specimen. All specimens were individually shot with a hot air stream (temperature approximately 1300C). Temperature readings were taken for each sheet. The hydrated specimen exhibited greater evaporative cooling over its dry counterpart. 12.5 wt% was shown to have the best evaporative cooling mechanism. Experiments were repeated to show that the polyacrylic could reabsorb water. This study illustrates proof of concept utilizing polyacrylic acid as an evaporative cooling material.

No description available.

Thesis (M.S.)--University of North Texas, Dec., 2008. / Title from title page display. Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2000. / Typescript (photocopy). Includes bibliographical references (leaves 81-85). Also available on the World Wide Web.

The sample used for evaporative cooling system is Fabric defender 750 with Shelltite finish. From the experimental data and equations we have diffusion coefficient of 20.9 ± 3.71 x 10-6 m2/s for fabric with one layer with 17%-20% fluctuations from the theory, 27.8 ± 4.5 x 10-6 m2/s for fabric with two layers with 6%-14% fluctuations from the theory and 24.9 ± 4.1 x 10-6 m2/s for fabric with three layers with 13%-16% fluctuations from the theory. Since the thickness of the fabric increases so the mass transport rate decreases so the mass transport resistance should be increases. The intrinsic mass resistances of Fabri-1L, Fabri-2L and Fabri-3L are respectively 104 ± 10.2 s/m, 154 ± 23 s/m and 206 ± 26 s/m from the experiment.

An investigation was performed to demonstrate system design for the delivery of water required for evaporative cooling of a proton exchange membrane fuel cell (PEMFC). The water delivery system uses spray nozzles capable of injecting water directly and uniformly to the nickel metal foam flow-field (element for distributing the reactant gases over the surface of the electrodes) on the anode side from which water can migrate to the cathode side of the cell via electroosmotic drag. For an effective overall cooling, water distribution over the surface of the nickel foam has to be uniform to avoid creation of hotspots within the cell. A prototype PEMFC structure was constructed modeled after a 35 kW electrical output PEMFC stack. Water was sprayed on the nickel metal foam flow-field using two types of nozzle spray, giving conical fog type flow and flat fan type flow. A detailed investigation of the distribution pattern of water over the surface of the nickel metal flow field was conducted. The motive behind the investigation was to determine if design parameters such as type of water flow from nozzles, vertical location of the water nozzles above the flowfield, area of the nozzles, or operating variables such as reactant gas flow had any effect on water distribution over the surface of the Ni-metal foam flow field. It was found that the design parameters (types of flow, area and location of the nozzle) had a direct impact on the distribution of water in the nickel metal foam. However, the operating variable, reactant gas flow, showed no effect on the water distribution pattern in the Ni-foam.

Thesis (Ph. D.)--Washington State University, December 2008.. / Title from PDF title page (viewed on July 10, 2009). "School of Mechanical and Materials Engineering." Includes bibliographical references (p. 176-187).

Thesis (M.S.)--University of Wyoming, 2007. / Title from PDF title page (viewed on June 22, 2009). Includes bibliographical references (p. 72-73).

Made available in DSpace on 2014-06-11T19:35:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T19:05:51Z : No. of bitstreams: 1 camargo_jr_dr_guara.pdf: 1019492 bytes, checksum: 2297d5279bcff4ccbedcb325ccb31939 (MD5) / O resfriamento evaporativo consiste na utilização da evaporação da água através da passagem de um fluxo de ar, provocando a redução na temperatura do ar e, apesar de utilizarem tecnologia relativamente simples, ainda são pouco utilizados para o condicionamento de ar em regiões de clima úmido. Este trabalho realiza um estudo dos potenciais e limitações de sistemas de condicionamento de ar por resfriamento evaporativo e evaporativo-adsortivo quando utilizados com o objetivo de propiciar conforto térmico ao homem e reduzir o consumo de energia. Apresenta-se, inicialmente, o princípio de funcionamento de sistemas de resfriamento evaporativo e de desumidificadores por adsorção. A seguir, apresentam-se os resultados dos ensaios de desempenho realizados em um resfriador evaporativo direto e propõe-se um novo sistema a ser utilizado em regiões em que as condições de conforto não podem ser supridas pelo resfriamento evaporativo somente. Estuda-se a aplicação desses sistemas a diversas cidades, caracterizadas por diferentes condições climáticas e conclui-se que os sistemas de resfriamento evaporativo acoplados a um desumidificador adsortivo apresentam perspectivas promissoras, principalmente para aplicação em condicionamento de ar onde existem fontes de calor de baixo custo ou calor residual disponível. A análise das condições do ar de insuflamento demonstra a viabilidade da utilização do sistema proposto para conforto térmico humano em regiões de clima úmido como uma alternativa aos sistemas convencionais de condicionamento de ar, poupando energia e protegendo o meio ambiente. / Evaporative cooling consists in using water evaporation through the passage of an air flow, thus decreasing the air temperature. In spite of using simple technology, it is seldon used for air conditioning in humid climate regions. This thesis develops a methodology that can be used to establish potentials and limitations of air conditioning systems by evaporative and desiccant cooling when used for human thermal comfort and lower power consumption. Firstly, the operational principles of evaporative cooling and dehumidification by adsorption systems are presented. Next, the results of performance tests developed on a direct evaporative cooler are described. Finally, a new system to be used in regions where the thermal comfort conditions cannot be supplied only by evaporative cooling is proposed. The applications of this system in several cities, characterized by different climate conditions are studied. It concluded that evaporative cooling systems coupled to a dehumidification adsorption system present promising perspectives, mainly to low cost air conditioning applications where residual heat sources are available. The analysis of the supply air conditions shows the feasibility of the proposed system for human thermal comfort in humid climates as an alternative to conventional air conditioning systems, saving energy and protecting the environment.

Evaporative cooling is an alternative and efficient method of cooling in dry climates. When a liquid evaporates into the surrounding gas, the energy required for the change of phase produces a cooling effect. The wet bulb depression is the measure of potential for evaporative cooling. Greater the wet bulb depression greater is the cooling effect, and vice versa. The residential desert cooler, apart from cooling the air increases the humidity of the air in the room by absorbing moisture from the water supplied to the cooler. This may result in an undesirable increase in humidity level. Allergies is an additional problem with direct evaporative coolers. Indirect evaporative cooling does not have these two drawbacks. In the present work a small indirect evaporative cooler is developed with a cross flow heat exchanger and the performance of the cooler is evaluated under controlled environmental conditions. The results are compared with the results of an analytical model developed by assuming constant water film temperature on the external wall of the heat exchanger tube. The experimental results of the cooler show a satisfactory agreement with the analytical values. Design calculations are presented to show the performance characteristics of indirect evaporative coolers under different temperature and humidity conditions of the ambient. It has been shown that reducing the heat exchanger tube diameter to around 2 mm results in better cooling effect. Climatic conditions of different Indian cities are discussed with respect to the expected effectiveness of indirect evaporative coolers.