ANALISIS TERGANGGUNYA SIRKULASI ZAT PENDINGIN PADA MESIN PENDINGIN DI MT. DEWAYANI

Riyyin, Muhamad Awwa, 52155775 T, 2020, “Analisis Terganggunya Sirkulasi Zat Pendingin Pada Mesin Pendingin di MT. Dewayani”. Program Studi Teknika, Program Diploma IV, Politeknik Ilmu Pelayaran Semarang, Pembimbing I: Bapak Drs. Edy Warsopurnomo, M.M., M.Mar.E. dan Pembimbing II: Ibu Irma Shinta Dewi, S.S., M.Pd. Pada setiap kapal, untuk menunjang kelancaran operasional diperlukan adanya mesin pendingin. Dengan adanya mesin pendingin bahan makanan dapat disimpan dengan baik dalam waktu relatif lebih lama dibanding jika disimpan ditempat yang tidak ada pendinginan. Dengan suhu ruangan pendingin yang terkontrol dapat memperpanjang daya tahan bahan makanan. Peneliti mengalami permasalahan yang mengindikasikan terganggunya sirkulasi zat pendingin. Terganggunya sirkulasi zat pendingin ini menyebabkan naiknya suhu pada ruangan pendingin. Peneliti menggunakan metode kualitatif dengan teknik analisa data yaitu Fishbone Analysis untuk menganalisa faktor-faktor penyebab terganggunya sirkulasi zat pendingin pada mesin pendingin dan pengumpulan data dengan observasi, wawancara, dan studi pustaka. Penelitian ini menggunakan rumusan masalah 1) Faktor-faktor apa saja yang menyebabkan terganggunya sirkulasi zat pendingin terhadap kerja mesin pendingin, dan 2) Bagaimana cara mengatasi gangguan sirkulasi media pendingin pada mesin pendingin. Hasil penelitian didapat faktor yang menyebabkan terganggunya sirkulasi zat pendingin pada mesin pendingin adalah masuknya minyak lumas kedalam sistem zat pendingin, kebocoran pada pipa kapiler, kondensor kotor yang mengakibatkan terhambatnya proses kondensasi zat pendingin, kesalahan prosedur pengoperasian mesin pendingin dan kurangnya konsisten seorang engineer. Cara mengatasi gangguan sirkulasi media pendingin pada mesin pendingin yang disebabkan oleh faktor-faktor tersebut yaitu melakukan Overhaul Kompresor(Piston, Ring Piston dan Liner), perawatan pada Oil Separator, perbaikan kebocoran pada pipa kapiler, perawatan kondensor, melakukan meeting bulanan dengan chief engineer untuk mengevaluasi konsistensi dan tanggung jawab dari engineer dan membuat laporan bulanan yang dikirimkan ke kantor, dan dengan memahami manual book serta bertanya kepada senior engineer atau chief engineer tentang perawatan dan pengoprasian mesin pendingin. Riyyin, Muhamad Awwa, 52155775 T, 2020, “Disruption Of Refrigerant Circulation Analysis In Refrigerator on MT. Dewayani”. Diploma IV Program, Techincal Program Study, Semarang Merchant Marine Polytecnic, 1 st Supervisor: Drs. Edy Warsopurnomo, M.M., M.Mar.E. and 2 nd Supervisor: Irma Shinta Dewi, S.S., M.Pd. On every ship, to support the operational smoothness required the existence of a Refrigerator Provision. With the existence of a Refrigerator Provision, food can be stored well in a relatively longer time than if stored in a place that does not have cooling. With a controlled cold room temperature can extend the durability of food. Researchers experiencing problems that indicate disruption of circulation of the refrigerant. The disruption of the circulation of these refrigerant causes the temperature to rise in the cold room. Researchers used qualitative methods with data analysis techniques namely Fishbone Analysis to analyze the factors causing the disruption of refrigerant circulation in the Refrigerator Provision and data collection by observation, interview, and literature study. This study uses the formulation of the problem 1) What factors cause the disruption of the circulation of the refrigerant to the work of the Refrigerator Provision, and 2) How to overcome the interference with the circulation of the refrigerant on the Refrigerator Provision. The results obtained by factors that cause the disruption of refrigerant circulation in the Refrigerator Provision is the entry of lubricant oil into the refrigerant system, leakage in the capillary pipe, dirty condenser which results in the inhibition of the process of condensation of the refrigerant, Refrigerator Provision operating procedures errors and a consistent lack of an engineer. How to overcome the interference of the refrigerant circulation in the Refrigerator Provision caused by these factors, namely doing Overhaul Compressors (Pistons, Piston Rings and Liners), maintenance of Oil Separator, repairing leaks in capillary pipes, condenser maintenance, conducting monthly meetings with the chief engineer to evaluating the consistency and responsibilities of the engineer and making monthly reports sent to the office, and by understanding the manual book and asking the senior engineer or chief engineer about the maintenance and operation of the cooling machine

Preliminary data set to assess the performance of an outdoor membrane photobioreactor

[EN] This data in brief (DIB) article is related to a Research article entitled 'Optimising an outdoor membrane photobioreactor for tertiary sewage treatment' [1]. Data related to the effect of substrate turbidity, the ammonium concentration at which the culture reaches nitrogen-deplete conditions and the microalgae growth rate under outdoor conditions is provided. Microalgae growth rates under different substrate turbidity were obtained to assess the reduction of the culture's light availability. Lab-scale experiments showed growth rates reductions of 22-44%. Respirometric tests were carried to know the limiting ammonium concentration in thismicroalgae-basedwastewater treatment system. Growth rates (m) of green microalgae Scenedesmus and Chlorella obtained under outdoor conditions; i.e. 0.40 d(-1) (R-2 = 0.993) and 0.43 d(-1) (R-2 = 0.995), respectively, can be useful to obtain optimum operating conditions of membrane photobioreactor (MPBR).This research work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO, Projects CTM2014-54980-C2-1-R and CTM2014-54980-C2-2-R) jointly with the European Regional Development Fund (ERDF), which are gratefully acknowledged. It also received support from the Spanish Ministry of Education, Culture and Sport via a pre-doctoral FPU fellowship to the first author (FPU14/05082).Gonzalez-Camejo, J.; Jiménez Benítez, AL.; Ruano, MV.; Robles Martínez, Á.; Barat, R.; Ferrer, J. (2019). Preliminary data set to assess the performance of an outdoor membrane photobioreactor. Data in Brief. 27:1-7. https://doi.org/10.1016/j.dib.2019.104599S172

Efficacy of different antifouling treatments for seawater cooling systems

In an industrial seawater cooling system, the effects of three different antifouling treatments, viz. sodium hypochlorite (NaClO), aliphatic amines (Mexel1432) and UV radiation, on the characteristics of the fouling formed were evaluated. For this study a portable pilot plant, as a side-stream monitoring system and seawater cooling system, was employed. The pilot plant simulated a power plant steam condenser, having four titanium tubes under different treatment patterns, where fouling progression could be monitored. The nature of the fouling obtained was chiefly inorganic, showing a clear dependence on the antifouling treatment employed. After 72 days the tubes under treatment showed a reduction in the heat transfer resistance (R) of around 70% for NaClO, 48% for aliphatic amines and 55% for UV, with respect to the untreated tube. The use of a logistic model was very useful for predicting the fouling progression and the maximum asymptotic value of the increment in the heat transfer resistance (DRmax). The apparent thermal conductivity (l) of the fouling layer showed a direct relationship with the percentage of organic matter in the collected fouling. The characteristics and mode of action of the different treatments used led to fouling with diverse physicochemical properties

An assessment of sub-standard water pressure in South African potable distribution systems

Sub-standard residual water pressures in urban water distribution systems (WDS) are a prevalent phenomenon in developing countries – South Africa being no exception. The phenomenon of sub-standard pressure is poorly understood, with intermittent supply ultimately resulting when there is no residual pressure left in the system. This research addressed the prevalence and extent of sub-standard pressures by using hydraulic models of potable WDS for 71 South African towns, located in 17 different South African municipalities geographically spread over the country. The hydraulic models included 539,388 modelled nodes, which were analysed to determine the number of nodes with sub-standard pressure heads during peak hour flow conditions. The results show that the residual pressure head was <24 m at 16.5% of the model nodes under peak hour flow conditions, with 6.7% of the nodes having pressure heads <12 m. In contrast, the results also report relatively high pressures in certain parts of the systems, far in excess of the minimum requirement, underlining the need for better pressure management at both high and low ranges. It was also noted that the South African design criterion is relatively stringent compared with some other countries and could potentially be relaxed in future

Predictors of Continued Breastfeeding at One Year among Women Attending Primary Healthcare Centers in Qatar: A Cross-Sectional Study

The number of babies in Qatar being exclusively breastfed is significantly lower than the global target set by the World Health Organization. The purpose of this study was to assess knowledge, attitude, and practice (KAP), selected barriers, and professional support as well as their association with continued breastfeeding at one year of age. A sample of Qatari and non-Qatari mothers ( = 195) who attended a well-baby clinic held at primary health care centers in Qatar completed a self-administered questionnaire. Descriptive analysis, the Pearson Chi-squared test, and logistic regression were performed. Around 42% of the mothers stopped breastfeeding when their child was aged between 0 and 11 months old. Mothers who had only one or female child stopped breastfeeding between the ages of 0 and 6 months ( = 0.025, 0.059). The more optimal the breastfeeding practices followed by the mothers, the older the age of the infant when they stopped breastfeeding ( = 0.001). The following factors were inversely associated with breastfeeding duration: the mother's perceptions that she "did not know how to breastfeed," or "wasn't making enough milk," and the need "to return to work/school", with = 0.022, 0.004, and 0.022, respectively. These findings present factors that should be considered when planning for health education and promotion programs to prolong breastfeeding duration in Qatar

Anaerobic biodegradation of oleic and palmitic acids : evidence of mass transfer limitations caused by long chain fatty acid accumulation onto the anaerobic sludge

Palmitic acid was the main long chain fatty acids (LCFA) that accumulated onto the anaerobic sludge when oleic acid was fed to an EGSB reactor. The conversion between oleic and palmitic acid was linked to the biological activity. When palmitic acid was fed to an EGSB reactor it represented also the main LCFA that accumulated onto the sludge. The way of palmitic acid accumulation was different in the oleic and in the palmitic acid fed reactors.Whenoleic acid was fed, the biomass-associated LCFA (83% as palmitic acid) were mainly adsorbed and entrapped in the sludge that became ‘‘encapsulated’’ by an LCFA layer. However, when palmitic acid was fed, the biomass-associated LCFA (the totality as palmitic acid) was mainly precipitated in white spots like precipitates in between the sludge, which remained ‘‘non-encapsulated.’’ The two sludges were compared in terms of the specific methanogenic activity (SMA) in the presence of acetate, propionate, butyrate, and H2CO2, before and after the mineralization of similar amounts of biomassassociated LCFA (4.6 and 5.2 g COD-LCFA/g of volatile suspended solids (VSS), for the oleic and palmitic acid fed sludge, respectively). The ‘‘non-encapsulated,’’ sludge exhibited a considerable initial methanogenic activity on all the tested substrates, with the single exception of butyrate. However, with the ‘‘encapsulated’’ sludge only methane production from ethanol andH2/CO2 was detected, after a lag phase of about 50 h. After mineralization of the biomass-associated LCFA, both sludges exhibited activities of similar order of magnitude in the presence of the same individual substrates and significantly higher than before. The results evidenced that LCFA accumulation onto the sludge can create a physical barrier and hinder the transfer of substrates and products, inducing a delay on the initial methane production. Whatever the mechanism, metabolic or physical, that is behind this inhibition, it is reversible, being eliminated after the depletion of the biomass-associated LCFA.Fundação para a Ciência e Tecnologia (FCT) Fundo Social Europeu (FSE

Sodium dodecyl sulfate allows the persistence and recovery of biofilms of Pseudomonas fluorescens formed under different hydrodynamic conditions

The effect of the anionic surfactant sodium dodecyl sulfate (SDS) on Pseudomonas fluorescens biofilms was investigated using flow cell reactors with stainless steel substrata, under turbulent (Re=5200) and laminar (Re=2000) flow. Steady-state biofilms were exposed to SDS in single doses (0.5, 1, 3 and 7 mM) and biofilm respiratory activity and mass measured at 0, 3, 7 and 12 h after the SDS application. The effect of SDS on biofilm mechanical stability was assessed using a rotating bioreactor. Whilst high concentrations (7 mM) of SDS promoted significant biofilm inactivation, it did not significantly reduce biofouling. Turbulent and laminar flow-generated biofilms had comparable susceptibility to SDS application. Following SDS exposure, biofilms rapidly recovered over the following 12 h, achieving higher respiratory activity values than before treatment. This phenomenon of posttreatment recovery was more pronounced for turbulent flow-generated biofilms, with an increase in SDS concentration. The mechanical stability of the biofilms increased with surfactant application, except for SDS concentrations near the critical micellar concentration, as measured by biofilm removal due to an increase in external shear stress forces. The data suggest that although SDS exerts antimicrobial action against P. fluorescens biofilms, even if only partial and reversible, it had only limited antifouling efficacy, increasing biofilm mechanical stability at low concentrations and allowing significant and rapid recovery of turbulent flow-generated biofilms.Fundação para a Ciência e a Tecnologia (FCT

Phycoremediation of municipal wastewater by microalgae to produce biofuel

Municipal wastewater (WW), if not properly remediated, poses a threat to the environment and human health by carrying significant loads of nutrients and pathogens. These contaminants pollute rivers, lakes and natural reservoirs where they cause eutrophication and pathogen-mediated diseases. However, the high nutrient content of WW makes it an ideal environment for remediation with microalgae that require high nutrient concentrations for growth and are not susceptible to toxins and pathogens. Given that an appropriate algal strain is used for remediation, the incurred biomass can be refined for the production of biofuel. Four microalgal species (Chlamydomonas reinhardtii, Chlorella sp., Parachlorella kessleri-I and Nannochloropsis gaditana) were screened for efficient phycoremediation of municipal WW and potential use for biodiesel production. Among the four strains tested, P. kessleri-I showed the highest growth rate and biomass production in 100% WW. It efficiently removed all major nutrients with a removal rate of up to 98% for phosphate after ten days of growth in 100% municipal WW collected from Delhi. The growth of P. kessleri-I in WW resulted in a 50% increase of biomass and a 115% increase of lipid content in comparison to growth in control media. The FAME and fuel properties of lipids isolated from cells grown in WW complied with international standards. The present study provides evidence that the green alga P. kessleri-I effectively remediates municipal WW and can be used to produce biodiesel