Development and Experimental Evaluation of an Automated Charge Testing Methodology for Domestic Refrigerators

Optimizing the refrigerant charge in a vapor compression cycle can lead to improvements in system performance and energy savings. Manufacturers often perform extensive experimental charge testing under different operating conditions to determine the optimal system charge of a certain product. However, the current de-facto industry standard procedure for performing such evaluation involves repeated charging and evacuating of equipment which is a time-consuming effort. In this work, an automated charge testing device and method were developed to perform a charge optimization for domestic refrigerators with the unit operating. This device consists of a combination of three solenoids to isolate a small calibrated volume of liquid refrigerant. This calibrated volume is typically around 2cc and allows a very small amount of refrigerant, usually less than 5 grams based on the density of liquid, to be charged into a unit with consistent accuracy and repeatability. This work also includes the development of a methodology for utilizing the device including software that automatically operates the device to charge the unit with additional refrigerant, collects and compares performance data, and detects when the optimal charge is reached to end the experiment. With the developed methodology, the entire procedure can be performed without human interaction saving a great amount of time and effort compared to conventional charge testing methods

Study on the improvement of the open TBM system and supporting equipment based on the Gaojiapu Coal Mine

In order to cope with multi-dimensional mine disasters in deep mines, enhance the adaptability of the open tunnel-boring machine (TBM) to the actual mine working face environment, and improve the excavation speed of the open TBM, based on the excavation project of Gaojiapu Coal Mine in Zhengtong Coal Industry, Shaanxi Province, this paper comprehensively considers the difficulties encountered by the TBM in the excavation process and improves the open TBM system and its supporting equipment. The research shows that removing the redundant system and supporting equipment of the open TBM can effectively solve the difficulties of the TBM entering the mine, such as loading and unloading, and turning; optimizing the open TBM shield, shortening the main beam, and setting the support platform and jumbolter system on the main beam can deal with the problem that the TBM support is not timely and easy to jam. Opening circular holes and installing slag cleaning guide plates on the main beam of the open TBM can timely clean up the waste slag on the main beam and protect the main beam from deformation. Installing a slag cleaning bucket wheel machine between the main beam of the open TBM and the trailer can reduce the accumulation of waste slag on the road ahead. Compared with ordinary excavation construction technology, the monthly average footage level of the open TBM after technical improvement is 300.88 m, which is 3.8 times that of the rock roadway general excavation and 1.6 times that of the rock roadway comprehensive excavation

Biological indicators of ecological quality in typical urban river-lake ecosystems: The planktonic rotifer community and its response to environmental factors

River-lake system is the framework of the "sponge city", tackling urban water problems of flooding. Rotifers, an essential zooplankton component of water ecosystems, are sensitive to environmental changes. However, the utility of rotifers as indicators of water quality in urban river-lake ecosystems is still unclear. We investigated the response of rotifer community to environmental factors and evaluated the availability of traditional taxonomic indicators and individual rotifer indicators in the river-lake ecosystem of Changde, south central China. A total of 95 rotifer species were identified in 15 sampling sites during a year survey. Rotifer abundance ranged from 1 (the Yuan River) to 2628 ind.L-1 (Lake Liuye). Temperature, water depth and trophic state were the key factors for spatial-temporal variation of rotifer community in the urban river-lake ecosystems. Individual rotifer indicators, biodiversity indices, the Brachionus: Trichocerca ratio and the Keratella-index were less useful in evaluating the trophic status in this study. However, we founded that the rotifer trophic state index (TSIROT) values and total rotifer abundance were most consistent with values of the comprehensive trophic level index (TLIc). Furthermore, TSIROT values showed stability and resistance to changes when the time horizon increased. This study suggests that the TSIROT index is a reliable indicator of water quality in river-lake ecosystems with high water depth variation. This is a pilot study for evaluating of reliable bioindicators for sponge city design. Longterm studies in more sponge cities should be taken to validate our findings