Analysis Of Temperature Gradients Research Articles

Development of the thermal performance model using temperature gradient analysis for optimized design of steam surface condenser

This paper presents a new method of evaluating the thermal performance of a steam condenser based on the temperature gradient between steam and cooling water. With reference to the experimental results, the pressure transition temperature (PTT), defined as the limiting cooling water temperature initiating insufficient heat removal over the applied heat load, was identified. An analytical methodology was developed to estimate the PTT for given geometrical and thermal-hydraulic conditions of the condenser system. The methodology was extended to a temperature gradient analysis (TGA) model for the performance evaluation of power plant-scale condensers by considering the effects of condensate inundation, tube loading pattern, steam shear, and fouling resistance. The assessment results of the TGA model showed good agreement with existing numerical and lumped-volume models, as well as measurement data of existing power-plant condenser systems. Its simplicity and strong capability to elucidate most of the design variables of the condenser make the TGA model suitable for executing many iterative calculations required when designing and optimizing the new condenser system.

PEMETAAN POTENSI PENANGKAPAN IKAN MENGGUNAKAN METODE SINGLE IMAGE (STUDI KASUS: PERAIRAN SELATAN JAWA)

Fishing Potential (PPI) is needed to increase fisheries productivity. Traditionally, fishermen use their senses and hereditary habits to determine PPI. Traditionally, fishermen use the five senses and hereditary habits to determine PPI. This method, in addition to being less efficient, can also lead to over-exploitation if fishing is carried out in the same place continuously. The existence of remote sensing technology can be used to determine PPI faster while considering aspects of approval and spatial distribution. One method of determining PPI is based on remote sensing data, mapping the thermal front area first before determining the PPI through manual interpretation based on pixel located between warm and cold water. Manual interpretation has limitations, it depends on humans and takes a long time. To overcome these limitations, in this study, the Single Image Edge Detection (SIED) method developed by Cayulla and Cornillon was applied in the form of a toolbox thus it could be used automatically. Sea Surface Temperature (SPL) data obtained from MODIS Level 2 (6 April 2018) was subsequently processed using this toolbox and successfully developed 22 PPI points in the southern part of Java Island. Meanwhile, PPI detection using the Temperature Gradient Analysis (TGA) method which is done manually produces 28 points. There are 20 locations of the same point using these two methods. Using the SIED method based on the toolbox can improve data, reduce human error with accuracy 64%.

A new approach to determine vapor pressures of compounds in multicomponent systems by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry

A method is described to determine vapor pressures of compounds in multicomponent systems simultaneously. The method is based on temperature-gradient analysis by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOFMS). Vapor pressures are determined with the aid of known vapor pressure values of reference compounds eluting before and after the analytes. Reference compounds with the same functionalities as the analytes are preferred, but when these are not available, the alkane series can be utilized. The number of compounds whose vapor pressures can be determined is limited only by the peak capacity of the chromatographic system. Although the lowest subcooled vapor pressure determined was 0.006Pa, for tetrahydroaraucarolone in an atmospheric aerosol sample, vapor pressures as low as 10−6Pa can be measured with the described set-up. Even lower values can be measured with higher GC temperatures and longer analysis times. Since only a few picograms of compound is required, in a mixture of any complexity, the GCxGC-TOFMS method offers unique sensitivity, rapidity, and comprehensiveness.