Noise test and control for household refrigerator compressor
Sound comfort becomes more and more important in residential houses. Home appliance is one of the main sources of indoor noise. Noise emission is a distinctive feature for the selection of the home appliances. Noise levels in household appliances are increasingly attracting attention from manufacturers and customers. Refrigerators as common appliances used by most families run continuously all day. It produces a lot of noises. National standards have published severe rules on the acceptable noise levels, and noise-free operation becomes the preferred choice of customers in the refrigerators choosing. Therefore, it is necessary to reduce the noise level of refrigerator. In this paper, the noise control study has been carried on a type of air-cooled household refrigerator. The noise level of the refrigerator was tested under different operation conditions at first. Then the maximum sound pressure level and noise characters were obtained by analyse the spectra of the noises. Test data shown that the refrigerator noises are mainly composed of compressor and fan noises. According to the characteristics of the compressor and fan noise, a method of using sound insulation board was proposed to reduce the compressor noise. Considering the actual installation restrictions and the compressor cooling demand, a kind of sound insulation board with holes was applied. Experimental studies indicated that the proposed noise control method can suppress the noise of the household refrigerator effectively.
STUDY ON THE REFRIGERATOR BOTTOM CABINET CAVITY ACOUSTIC BEHAVIOR
Recently, sound comfort has become important in residential houses and noise emission is a distinctive feature for the selection of the home appliances in the same energy class. Refrigerators run continuously when it is compared with other home appliances. Therefore, reduction of refrigerator noise is necessary and noise-free operation becomes the preferred choice of customers in the domestic refrigerators. Together with the fan, the compressor is a source of noise that contributes to most of the refrigerator’s overall noise level due to the existence of a rotary element and this element motion creates vibration and noise. In this study, acoustic behavior of bottom cabinet cavity, housing the compressor in a refrigerator, is investigated. The natural frequencies of the bottom cabinet cavity are investigated. Firstly, natural frequencies are determined with analytical method. Secondly, natural frequencies are determined with numerical analysis using the finite element model of the bottom cabinet cavity. Comparisons with the results of the analytical study verify the validity of the numerical solution. Finally, experimental study is carried out for validation of both models. It is seen that the sound pressure of the bottom cabinet of the refrigerator is higher at some frequencies. These frequencies are in close match with the natural frequencies of the bottom cabinet cavity of the refrigerator which can be determined with the analytical and numerical analysis. For some peak frequencies, results into noise reduction by using sound absorber materials are also presented.
Suitability and water quality criteria of an open drainage municipal sewage water at Coimbatore, used for irrigation.
Sanganur canal is the major open drainage system which has intricate linkage with storm water supply, domestic sewage and industrial effluent disposal. Water samples from various stations were collected and analysed for physicochemical parameters to assess the water quality of the Sanganur canal system. The study revealed that physicochemical parameters like pH, EC, TDS, DO, BOD, COD exceeded the permissible limit, clearly indicating the need of proper treatment of waste water before discharge into the Noyyal river.