Differences In Water Temperature Research Articles

Distribution and abundance of pteropods in the western Barents Sea

Abstract The abundance and horizontal distribution of three pteropod species, Limacina helicina, Limacina retroversa and Clione limacina were examined in the western entrance of the Barents Sea (Polar Front region) in August 2011. Sixteen samples were collected from 8 sampling sites located along a latitudinal transect. The southern part of the study area (south of 73°N) was dominated by L. retroversa, while L. helicina was mostly observed north of 73°N. Surface water temperature differences between the coldest and the warmest station were around 8°C. The highest density of L. retroversa was found in the south, near the Norwegian coast (nearly 52 000 ind. 1000 m−3), while the highest density of L. helicina was observed in the region of the Arctic water masses (nearly 13 000 ind. 1000 m−3). The sampled population of pteropods comprised mainly juvenile stages. Redundancy analysis (RDA) of the relationships between environmental factors (mean and surface salinity, mean temperature, sampling depth, chlorophyll concentration) and the population structure showed that mean temperature was the most important factor in the study area, explaining 70.5% of the pteropod community variation.

Effect of Effective Microorganisms (Em) and Molasses, Wheat Bran, and their Mixture in a Biofloc System on Microbial Protein Production, Water Quality, Growth Performance and Feed Utilization of Nile Tilapia (Oreochromis niloticus) Fingerlings.

The present experiment was carried out to investigate the effect of effective microorganisms, EM; carbohydrate sources as molasses, M; wheat bran, and their mixture in a Bio-floc (BF) system on microbial protein production, water quality, growth performance, and feed utilization of Nile tilapia (Oreochromis niloticus) fingerlings. Seven experimental treatments were designed as following: T1: control, fish were fed a basal diet without any addition of carbohydrate source. T2: T1 plus effective microorganisms (EM) in water media. T3: T1 with supplementary molasses (M) in water media. T4: T1 with supplementary wheat bran (WB) in water media. T5: T1 with supplementary of mixture from EM and M in the water media. T6: T1 with supplementary of mixture from EM and WB in the water media, and T7: T1 with supplementary of mixture from M and WB in the water media. Fish in each tank were fed with one of the experimental diets containing 22.49 % crude protein and 471.60 Kcal. gross energy /100g DM at feeding rate of 3% of the actual fish live body weight, two times daily (9.00am and 2.00 pm) for six days a week for 90 days experimental period. Fish were distributed randomly into fourteen indoor fiberglass tanks. Each treatment was conducted in two indoor circular fiberglass tanks of 1m diameter filled with 1000 litter of fresh water. Nile tilapia fingerlings with an average initial body weight of 47.5±0.05 (g/fish) were randomized stocked at the rate of 42 fish / tank. The results showed the followings:The water quality parameters showed no significant differences in water temperature (C0), pH value and DO (mg/l); however, there were marked differences in the values of total ammonia nitrogen (TA-N, mg/l) and Bio-floc (BF) concentrations (mg/l), with high values of TA-N and BF in tanks' water supplemented with different carbohydrate sources than control, especially with T6 which containing mixture of EM and WB in water media followed by T4 (WB), T3 (M), T5 (EM+M), T2(EM), and T6 (M+WB), respectively compared with T1 (control without carbohydrate source).Fish growth performance and feed utilization were significantly (P≤ 0.05) increased with EM and carbohydrate source supplementation than control. Also, T6 which containing a mixture of EM and WB gave the highest performance followed by WB (T4) and M (T3), respectively.Finally, the present results recommended the use of a mixture of effective microorganisms and wheat bran as a carbohydrate source in fish water tanks for optimal performance with best impacts on intensive tilapia culture reared under zero water exchange system.

Multi- effect air gap membrane distillation process for pesticide wastewater treatment

A multi-effect air gap membrane distillation (ME-AGMD) module for pesticide wastewater treatment is studied with internal heat recovery, sensible heat of brine recovery, number of stages and the use of fresh feed as cooling water in a single module is implemented in this study. A flat sheet polytetrafluroethylene (PTFE) membrane was used in the 4-stage ME-AGMD module. The maximum value of permeate flux could reach 38.62 L/m2h at feed -coolant water temperature difference about 52\'C. The performance parameter of the module like, specific energy consumption and gain output ratio (GOR) was investigated for the module with and without heat recovery. Also, the module performance was characterized with respect to the separation efficiency of several important water quality parameters. The removal efficiency of the module was found to be >98.8% irrespective water quality parameters. During the experiment the membrane fouling was caused due to the deposition of the salt/crystal on the membrane surface. The membrane fouling was controlled by membrane module washing cycle 9 h and also by acidification of the feed water (pH=4) using 0.1M HCl solution.

Air-sea heat flux control on the Yellow Sea Cold Water Mass intensity and implications for its prediction

The Yellow Sea Cold Water Mass (YSCWM), which occurs during summer in the central Yellow Sea, plays an important role in the hydrodynamic field, nutrient cycle and biological species. Based on water temperature observations during the summer from 1978 to 1998 in the western Yellow Sea, five specific YSCWM years were identified, including two strong years (1984 and 1985), two weak years (1989 and 1995) and one normal year (1992). Using a three-dimensional hydrodynamic model, the YSCWM formation processes in these five years were simulated and compared with observations. In general, the YSCWM began forming in spring, matured in summer and gradually disappeared in autumn of every year. The 8°C isotherm was used to indicate the YSCWM boundary. The modelled YSCWM areas in the two strong years were approximately two times larger than those in the two weak years. Based on the simulations in the weak year of 1995, ten numerical experiments were performed to quantify the key factors influencing the YSCWM intensity by changing the initial water condition in the previous autumn, air-sea heat flux, wind, evaporation, precipitation and sea level pressure to those in the strong year of 1984, respectively. The results showed that the air-sea heat flux was the dominant factor influencing the YSCWM intensity, which contributed about 80% of the differences of the YSCWM average water temperature at a depth of 50m. In addition, the air-sea heat flux in the previous winter had a determining effect, contributing more than 50% of the differences between the strong and weak YSCWM years. Finally, a simple formula for predicting the YSCWM intensity was established by using the key influencing factors, i.e., the sea surface temperature before the cooling season and the air-sea heat flux during the cooling season from the previous December to the current February. With this formula, instead of a complicated numerical model, we were able to roughly predict the YSCWM intensity for the following summer by using the data available online in winter.

Body-length frequency and spatial segregation of the North Pacific spiny dogfish Squalus suckleyi in Tsugaru Strait, northern Japan

The present study elucidated the length structure and habitat segregation of North Pacific spiny dogfish (SPD) Squalus suckleyi in the Tsugaru Strait of northern Japan. Length–frequency distributions using kernel density estimation were determined for SPD captured by the bottom longline fishery landed at Minmaya from 1999 to 2011 and at Ohma from 2007 to 2011. Length–frequency distributions significantly differed between landings at the two ports; SPD at Minmaya were on average larger (65–85 cm precaudal length: PCL) than at Ohma (55–75 cm PCL). This difference is evidence of the length-based spatial segregation of the SPD. The seasonal landing pattern of the SPD was also different between the two ports. The SPD landed at Minmaya were largest during February–June and SPD < 75 cm PCL were caught at Ohma throughout the year. This different landing pattern was related to seasonal differences in bottom-layer water temperatures between the two fishing grounds. Females were thought to be dominant at Minmaya, whereas males dominated in most of the catches at Ohma. These results suggest spatial patterns of sexual segregation for this species in the Tsugaru Strait and require elucidation of the SPD stock condition at Minmaya and Ohma.

ANALISIS PERBANDINGAN UNJUK KERJA PEMANAS AIR TENAGA SURYA TIPE PLAT DATAR DENGAN SISTEM SINGLE DAN DOUBLE CUTOFF

Abstract: Warm water is needed by human being to take a bath, wash their clothes, their dishes etc. By the photothermal conversion, the solar energy can be used to heat the water. Flat solar collector is a tool which is used to capture energy of the sun radiation then convert it into heat to heat up water in collector’s pipes. The number of glass cover used effects the performance and efficiency of the collector. From this research, it is found that the efficiency of the collector is better when the cover used are two glasses than one glasses. The temperature difference of incoming and outgoing water in the collector using two glasses 15 ̊C higher than that of one glass.

Kongsfjorden and Hornsund hydrography – comparative study based on a multiyear survey in fjords of west Spitsbergen

Summary A recent study has shown increased warming in the fjords of west Spitsbergen. Their location is critical, as they are situated along the main northward pathway of Atlantic Water (AW) which is a great source of heat to the Arctic Ocean and the fjords. In the light of ongoing warming, we aim to discuss differences between the fjords under northward transformation of oceanic waters. We compared summer hydrographic conditions in two fjords located in two opposite ends of west Spistbergen: Hornsund in the south and Kongsfjorden in the north. The study is based on high resolution CTD measurements collected during Arctic cruises between 2001 and 2015. The emphasis was put not only on differences in water temperature, salinity and water masses but also the freshwater content ( FWC ), AW transport and heat delivery to the fjords. In general, the water in Kongsfjorden is on average 1°C warmer and its salinity is higher by 0.5 compared to Hornsund. It is also characterized by two times greater transport of AW and heat delivery to the fjord. On the other hand, Hornsund reveals two times higher FWC . Both fjords undergo a gradual warming due to an increased presence of Atlantic origin waters. The ongoing warming is accompanied by an increase in variability of temperature and salinity dependent on the domination of the Sorkapp Current (SC) or the West Spitsbergen Current (WSC) on the West Spitsbergen Shelf (WSS). Nonetheless, Hornsund remains more Arctic-type fjord compared to Kongsfjorden, due to stronger blocking by SC.

English

There is evidence that ammonia, hydrogen sulphide and dissolved oxygen are implicated in fish kills occurring on the Lake Malawi shores of Karonga town. Exposure to fish is influenced by strong winds while water temperature differences cause upwelling and fish mortalities in surface waters. The vulnerability of fish in Karonga town to physico-chemical factors was computed from secondary sources data obtained in 2000 to 2016 regarding lethal and sub-lethal limits; this has helped to broaden our understanding of aquatic risk factors in this area. Equilibria relationships of ammonia (NH3 + H2O = NH4+ + OH-; K = 10-4.74; 2.70-4.28 &micro;g.L-1 at depth of 100 to 200 m) and hydrogen sulphide (H2S = HS- + H+; K= 10-7.01; 54.9-82.5 mg.L-1 at a depth of 0-150 m) are imputed to have been implicated in the cause of a spate of fish kills.&nbsp; Uranium fallout might also be implicated but further analysis on actual exposure is needed to confirm this. Inferences of fish vulnerability have been drawn from studies done elsewhere on similar freshwater fish but under controlled conditions. While fish catches temporarily improved in 2007-2008 and 2010-2011, changes in fish diversity have been consistent, such as the disappearance of Ntchila (Labeo mesops), decline of Chambo (Oreochromis species) and the dominance of sardine type Usipa (Engraulicyprus sardella). Therefore, other sources of risks are over-fishing and climate change; the latter is evidenced by warming of the deep water columns, reduced dissolved oxygen and declining Lake Malawi water levels. The significance of fish by-catch recorded as &lsquo;others&rsquo; indicates that a high number of fish species remain scientifically undescribed, hence the need for further taxonomic studies. Fish catches as per caput fish supply for Karonga District (19.5-38 kg) are above the current national average of 4.0 go 5.8 kg. Since fish provides Karonga communities with affordable animal protein, it significantly contributes to food security for the town. More than 5,500 people depend directly on fishing, representing 10% of the population of Karonga. Fisheries are a driver to rural commercialization for businesses of up to 22,000 people; hence, it is critical to people&rsquo;s livelihoods and incomes at the local level. Therefore, this study confirms what has commonly been observed for Karaonga town; that fish as a nutrition and income source should be factored into studies dealing with risks to livelihoods of Karonga town communities; even where this might require indirect methods of assessment. Key words: Fish catches, Karonga town, Lake Malawi, fish diversity, per caput fish supply, thermodynamic concentrations (H2S/HS-; NH3/NH4+).

The Algae Testbed Public-Private Partnership (ATP3) framework; establishment of a national network of testbed sites to support sustainable algae production

Well-controlled experiments that directly compare seasonal algal productivities across geographically distinct locations have not been reported before. To fill this gap, six cultivation testbed facilities were chosen across the United States to evaluate different climatic zones with respect to algal biomass productivity potential. The geographical locations and climates were as follows: Southwest, desert; Western, coastal; Southeast, inland; Southeast, coastal; Pacific, tropical; and Midwest, greenhouse. The testbed facilities were equipped with identical systems for inoculum production and open pond operation and methods were standardized across all testbeds to ensure accurate measurement of physical and biological variables. The ability of the testbed sites to culture and analyze the same algal species, Nannochloropsis oceanica KA32, using identical pond operational and data collection procedures was evaluated during the same seasonal timeframe. This manuscript describes the results of a first-of-its-kind coordinated testbed validation field study while providing critical details on how geographical variations in temperature, light, and weather variables influenced algal productivity, nitrate consumption, and biomass composition. We found distinct differences in growth characteristics due to the geographic location and the resulting climatic and seasonal conditions across the sites, with the highest productivities observed at the desert Southwest and tropical Pacific regions, followed by the Western coastal region. The lowest productivities were observed at the Southeast inland and Midwest greenhouse locations. These differences in productivities among the sites correlated with the differences in pond water temperature and available solar radiation. In addition two sites, the tropical Pacific and Southeast inland experienced unusual events, spontaneous flocculation, and unusually cold and wet (rainfall) conditions respectively, that negatively affected outdoor algal growth. In addition, minor variability in productivity was observed between the different experimental treatments at each site, much smaller compared to differences due to geographic location. Finally, the successful demonstration of the coordinated and standardized operation of the testbed sites established a rigorous basis for future validation of algal strains and operational conditions and protocols across a geographically diverse testbed network.

Reservoir Souring – Latest developments for application and mitigation

Sulphate-reducing prokaryotes (SRP) have been identified in oil field fluids since the 1920s. SRP reduce sulphate to sulphide, a toxic and corrosive species that impacts on operational safety, metallurgy and both capital and operational cost. Differences in water cut, temperature, pressure and fluid chemistry can impact on the observed H2S concentration, meaning that an increase in H2S concentration does not always correlate with activity of SRP. However it wasn’t until the 1990s that SRP activity was accepted as the leading cause of reservoir souring (i.e. an increase in H2S concentrations) in water flooded oil fields.The process of sulphate-reduction has been well documented at the genetic, enzymatic and physiological level in pure cultures under laboratory conditions. DNA sequencing has also identified new groups of microorganisms, such as archaea which are capable of contributing to reservoir souring. This has led to some recent advances in microbial control and detection, however, despite this, many of the methods used routinely for microbial control and detection are over a century old. We therefore look towards emerging and novel mitigation technologies that may be used in mitigating against reservoir souring, along with tried and tested methods. Modelling and prediction is another important but often under-used tool in managing microbial reservoir souring. To be truly predictive, models need to take into account not only microbial H2S generation but also partitioning and mineral scavenging. The increase in ‘big data’ available through increased integration of sensors in the digital oil field and the increase in the DNA sequencing capabilities through next-generation sequencing (NGS) therefore offer a unique opportunity to develop and refine microbial reservoir souring models. We therefore review a number of different reservoir souring models and identify how these can be used in the future.With this comprehensive overview of the current and emerging technologies we will highlight areas where significant development effort could generate rewards that can improve detection, prediction and control of microbial reservoir souring.

Difference in Size at Maturity in Annual and Overwintering Generations in the Tanaidacean Zeuxo sp. in Oshoro Bay, Hokkaido, Japan.

We investigated the life cycle of the tanaidid Zeuxo sp. 1 (Crustacea: Peracarida: Tanaidacea), which lives epiphytically in dwelling tubes on the algae Sargassum spp. and Neorhodomela aculeata in Oshoro Bay, Hokkaido, Japan. We obtained data on its population size distribution, age structure, and reproductive phenology through monthly sampling from April 2011 to June 2012. From these data, we detected an overwintering group (F0) that arises from mancae that are released in autumn, overwinters, reproduces the following spring, and then disappears. The overwintering group produces mancae (F1) that reach maturity and themselves reproduce within six weeks after release; the F1, mancae give rise to an F2 and possibly an F3 generation within a single summer. We refer to individuals that reproduce in the same summer that they were released as the 'annual group'. Reproduction overall was restricted to the period from May to October, when the seasurface temperature exceeded 10°C. During both years, overwintering females first became reproductive in May. Reproduction in the annual group began in June and continued through mid-October. Mancae were observed in samples from June through October. The two groups differed significantly in size at reproduction; compared to the annual group, females in the overwintering group reproduced at larger minimum and average body sizes, and males began to express enlarged chelae, a secondary sexual character, at a larger size. The difference in size at maturity may be related to the differences in water temperature during the main period of growth and maturation.

Estuarine Plume: A Case Study by Satellite SAR Observations and &lt;italic&gt;In Situ&lt;/italic&gt; Measurements

Estuary plumes on the western Louisiana continental shelf in the Gulf of Mexico, outside of constricted channels of the Sabine and Calcasieu Lakes were observed on two RADARSAT-1 synthetic aperture radar (SAR) images. The in situ data showed a change in salinity of ~2–3 PSUs across the front on the northwest edge of the plume, corresponding to locations of vertical salinity variation of 5.5–7.5 PSU. Velocity magnitude outside of the inlet reached more than 2.3 ms $^{{\mathrm {-1}}}$ seaward and a brackish lens in the upper 4.5 m of the water column, the spread of which contributed to the development of a plume. The volume of brackish water within the plume was estimated an order of magnitude larger than the volume output from the Calcasieu River within an entire ebb tidal period. This implies that the plume was formed during multiple tidal cycles and it sustained during the flood tides because only weak diurnal tides exist. Both satellite and in situ observations showed an interesting western intensification of the plume. An analysis to the momentum/vorticity equations suggests that the western intensification is due to the asymmetry of the vorticity-divergence relationship under the Coriolis force. This can also be enhanced by an ambient coastal current that strengthens the convergence at the front. Estuary plumes are shown as bright and dark features in two SAR images. Results from a radar model simulation and in situ water temperature data showed that the SAR observed plume features were dominated by the water temperature differences.

Early drivers of Black Mangrove (Avicennia germinans) leaf litter decomposition in the water column

Sequestration of carbon and nutrients, and sustained productivity of estuaries depend on organic turnover and nutrient remineralization. Decomposition of abundant plant material produced by mangroves and other macrophytes in estuaries occurs in both the sediments and the water column. Early and intense processing could be more common in the water. In a previous study, in situ decomposition rates of Black Mangrove (Avicennia germinans) leaf litter suspended in the water column differed among four estuaries in south Texas with moderate differences in salinity, water temperature, available nitrogen (N), and tidal flow. A series of microcosm experiments were conducted to determine the influence, within observed ranges in the estuaries, of these water variables on mass loss of mangrove leaf litter over 60 days. High salinity (66 psu) delayed decomposition, but low temperature (20°C) was a retardant at lower salinities (20–43 psu). Water turbulence greatly accelerated mass loss, whereas N additions and the presence of sediments had minimal effects. The faster decomposition observed in the estuaries compared to the microcosms may be explained by the synergistic effect of these and other environmental factors.

2009 개정 교육과정 초등과학에서 제시된 해륙풍 모형실험 분석 및 개선 방안

The purpose of this study is to analyze the problems of land and sea breeze model experiment that has presented in <TEX>$5^{th}$</TEX> grade curriculum in chapter "Weather and our lives" and makes better model simulation so that learners can have better and more effective way to study it. To survey the opinions from dedicated teachers about land and sea breeze model experiment, we produced the survey through interview with science exclusive teacher from M elementary school. An elementary science education expert, 3 men of science EdD modified and complemented survey and started Delphi survey to 12 science teachers who have career teaching more than 3 years. The problems found in this survey were 'one heat bulb, short heating time, small temperature difference of water and sand, lack of class time, empty space between sand and water, back of transparent boxes, little amount of scent and the location of the it' etc. But the most of all, it is hard to see the successful result of the experiment. Based on these kinds of investigations, and lots of trial and error, redesigned the new model experiment that has the most similarity to the real one and high probability of success. According to this, it was able to see the smoke forms horizontal movement along the sand and the smoke goes in one circulation cycle. through this experiment, we made a conclusion that although those scientific experiments in textbook were developed through lots of considerations of expert, to consider the aspect of consumer, it needs to reach the educational agreement about simulation experiment so that It can lead to successful experiment and high quality education.

Experimental study of a novel integrated system of indirect evaporative cooler with internal baffles and evaporative condenser

In this study, the performance of a novel integrated system of indirect evaporative cooler with internal baffles as air pre-cooling unit and evaporative condenser has been experimentally investigated. For this purpose, the experimental setup consisting of an indirect evaporative cooler with internal baffles followed by an evaporative condenser contains the hot water serpentine tubes with external thin film cotton layer was designed, constructed and tested. The influences of pre-cooling unit and the external thin film cotton layer on the performance of the evaporative condenser are investigated. The experimental results show that, for increasing the air flow rate from 250 to 1450 m3/h, the temperature difference of hot water through the evaporative condenser change in the ranges between 13 and 24.9°C for the case without pre-cooling unit, 17.6–38.4°C for using the pre-cooling unit with internal baffles and with use the thin film cotton layer. Also, the rate of change of the cooling load is in the ranges between 166 and 318kW for case without pre-cooling unit, but for using the pre-cooling unit with internal baffles and with use the thin film cotton layer the cooling load change between 224.7 and 490.3kW. For using the external thin film cotton layer on the tubes of cross flow heat exchanger and with use the pre-cooling unit with internal baffles before the evaporative condenser the percentage increases in the cooling load change between 35.4 and 54.2% compared to the evaporative condenser without pre-cooling unit.

Review: Rusticle Formation on the RMS Titanic and the Potential Influence of Oceanography

Meter length iron-rich rusticles on the RMS Titanic contain bacteria that reportedly mobilize iron from the ship structure at a rate that will reduce the wreck to rust in decades. Other sunken ships, such as the World War II shipwrecks in the Gulf of Mexico (GOM) are also similarly covered. However, at the GOM sites, rusticles are only centimeters in length. Minimal differences in water temperature (a few °C) between the two sites and comparable exposure times from wreckage to discovery cannot rationalize the extreme differences in rusticle length. One possible explanation for the observed difference in rusticle size is the differing amounts of dissolved or colloidal iron at the two locations.

Upwelling or differential cooling? Analysis of satellite SST images of the Southeastern Baltic Sea

The results of comparative analysis of sea surface temperature variations along horizontal sections in the coastal zone are given. The data used had been taken by MODIS spectroradiometers (Aqua, Terra) in the Southeastern Baltic, in periods of coastal upwelling—in the periods of autumn differential cooling over coastal continental slopes (facilitating water subsidence along these slopes). Studying 135 SST images of coastal upwelling events in May–October 2000–2014 and four cooling events in October–November 2002, 2004, 2005, and 2009 revealed the specific features of the shape of horizontal temperature profiles on sea surface along sections over coastal continental slopes. In addition to the higher differences between water surface temperatures in the deep and coastal parts of the sea (up to 14°C), upwelling features an appreciable distance from the cold-water core to the coast (up to 3–15 km) and a variable shape of horizontal profiles of water temperature on the sea surface along the sections. Conversely, during autumn differential cooling, water temperature difference on the surface is relatively small, the shape of the dependence of surface water temperature on the distance to the shore does not change over time, varies only slightly with the alongshore displacement of the section, and shows low sensitivity to bathymetry and even to wind effect. Thus, the analysis of the shape of the temperature on the sea surface along horizontal sections over coastal continental slopes enables the diagnostics of the regime of vertical water exchange in the coastal zone.

An Experimental Study on the Inner and Outer Glass Cover Temperatures of Solar Still

The glass cover of a solar still plays a major role in its performance and efficiency since the output depends directly on the water and glass cover temperature difference. In most of the experimental studies, the outer glass cover temperatures were recorded and considered as the glass cover temperature for calculations, however the condensation on the glass cover surface depends more on the inner surface temperature than the outer. An experimental study was conducted in order to study the difference between the inner and the outer glass cover temperature difference in a conventional basin type solar still and a low thermal inertia solar still obtained by modifying the conventional still. It was observed that for the conventional still, the temperature difference was maximum upto7.14% at noon and insignificant in the morning and evening hours. For the low thermal inertia still, the difference was more upto 10.2% at around 11:00 hrs and zero during the early morning and the evening hours. A significant difference in the glass cover temperature curves for the two different types of solar stills can be seen.

Study on the pulsed flow control on radiant cooling and heating systems in part load

In this paper, we propose a pulsed flow control of the radiant system with a fixed on-time to replace the storage water in pipes and a variable off-time to regulate the capacity. We developed a three-dimension numerical model to simulate the performance of the radiant heating and cooling system in the pulsed flow control method. Through numerical simulation on radiant systems with various thermal masses, the average supply and return water temperature difference and surface temperature non-uniformity were compared between the pulsed flow control and the variable flow rate control. The results demonstrate that the pulsed flow control achieves a comparable supply and return water temperature difference and pump energy consumption to the variable flow rate control. However, the pulsed flow control method saves the initial cost by substituting proportional valves by two-way position valves and has a higher controllability in part load. Furthermore, the pulsed flow control yields a smaller surface temperature non-uniformity than variable flow rate control, which is beneficial to reduce the condensation risk in cooling condition.

Heat-transfer characteristics of ammonia-water falling film generation outside a vertical tube

A heat transfer experimental of vertical out-tube falling film was conducted with different inlet spray density of ammonia-water solution and inlet hot water temperature. The inlet liquid mass concentration was selected as 60% of ammonia. The experiments showed that the overall heat transfer coefficient increases with the increase of inlet spray density and a maximum overall heat transfer coefficient could be obtained in an optimum spray density of ammonia-water solution, ?, between 0.26 and 0.29 kg/ms. The generation of ammonia vapor outside the vertical falling film had a similar trend with the overall heat transfer coefficient basing on different spray density. The effect of hot water temperature difference, ?T, on overall heat transfer coefficient showed that ?T between 10 and 13 K is the optimum temperature difference of the vertical falling film generation