Application of the Natural Refrigerant Mixture R-290/DME to a Soft Ice Cream Refrigerator

2016 ◽  
Vol 24 (04) ◽  
pp. 1650027 ◽  
Author(s):  
Nae-Hyun Kim
Keyword(s):  
Ozone Depletion ◽  
Ice Cream ◽  
Formation Time ◽  
Actual Usage ◽  
Refrigerant Mixture ◽  
Expansion Valve ◽  
Valve Opening ◽  
Natural Refrigerant ◽  
Optimum Charge

Due to the ozone depletion issue, R-502, which had long been used as the refrigerant of an ice cream refrigerator, has been replaced by R-404A. However, global warming potential (GWP) of R-404A is high, and thus, a replacement refrigerant is necessary in the long term. Natural refrigerants, such as R-290 or DME (dimethylether), could be a choice. In this study, an ice cream refrigerator cycle was optimized using R-290/DME mixture (mass fraction 65/35). The optimization was accomplished through a search for the proper refrigerant charge amount and the opening of the expansion valve. For the present ice cream refrigerator having 2.8[Formula: see text]L freezer volume, the optimum charge amount was 900[Formula: see text]g, and the optimum valve opening was [Formula: see text]120[Formula: see text]. At this configuration, the ice cream formation time was 3[Formula: see text] 6[Formula: see text] and COP was 2.0. The ice cream formation time was much shorter than when R-404A was used, and the COP was increased by more than 100%. For actual usage of the refrigerant, however, the flammability issue of the R-290/DME mixture should be cleared.

Optimization of the Water Spray Nozzle, Refrigerant Charge Amount and Expansion Valve Opening for a Unitary Ice Maker Using R-404A

2017 ◽  
Vol 25 (03) ◽  
pp. 1750025 ◽  
Author(s):  
Nae-Hyun Kim
Keyword(s):  
Ozone Depletion ◽  
Heat Transfer Performance ◽  
Condensation Temperature ◽  
Refrigeration Cycle ◽  
Evaporation And Condensation ◽  
Start Up ◽  
Expansion Valve ◽  
Valve Opening ◽  
Ice Production ◽  
Optimum Charge

R-502, which had long been used as the refrigerant of a unitary ice maker, has been replaced by R-404A due to ozone depletion. In this study, the refrigeration cycle of a unitary ice maker was optimized using R-404A. The optimization was accomplished through a search for the proper refrigerant charge amount and the opening of the expansion valve. For the present ice maker having 24 ice cups, the optimum charge amount was 580[Formula: see text]g and the optimum valve opening was “0”. At this configuration, the ice making time was 12[Formula: see text]min 55[Formula: see text]sec, ice production was 4.46[Formula: see text]kg/h and COP was 0.439. After the initial start-up period, both condensation and evaporation temperature gradually decrease with time. As ice builds up in the cup, the heat transfer performance of the evaporator decreases, which results in the decrease of the evaporation and condensation temperature. Through CFD and relevant experiments, optimum nozzle slit width and nozzle to cup distance were obtained.

scholarly journals Co-Evolution of the Presence of Long Lasting Insecticide Treated Nets and Plasmodium falciparum Welch, 1897 Prevalence in Cahata Village (Benguela Province, Angola) during a Village Scale Long-Term of Malaria Vector Control Program

2021 ◽  
pp. 21-32
Author(s):  
P. Carnevale ◽  
J. C. Toto ◽  
V. Foumane ◽  
S. Carnevale ◽  
F. Gay
Keyword(s):  
Plasmodium Falciparum ◽  
Vector Control ◽  
Rebound Effect ◽  
Control Program ◽  
Control Programme ◽  
Malaria Vector Control ◽  
Insecticide Treated Nets ◽  
Cross Sectional ◽  
Actual Usage

A long term village scale vector control programme was implemented since 2007 in 8 villages around Balombo town (Benguela Province) to compare the efficacy of 4 methods of vector control (1,2). One of them are deltamethrin treated Long Lasting Nets (“LLIN”) “Perma©Net 2.0” with a complete coverage of every sleeping units in 2008 in 2 villages, Caala and Cahata. Cahata was surveyed for 10 years with regular parasitological cross sectional parasitological surveys. During the 3 years following LLIN implementation, a check of their actual usage in every house, or on sleeping units of each patient examined during every parasitological surveys showed that 3 years after the full LLIN distribution less than 50% were still in use, and this percentage regularly decreased to reach 10% and less in 2015 (with 0% during the survey done in October 2005). But Plasmodium falciparum prevalence still decreased with low level until 2014 then it started (slightly) increasing in 2015, and the following years, which correspond to both the National malaria outbreak and the least percentage of LLIN used! But even at that time the plasmodial load was significantly lower in “LLIN users” than in non users showing some maintained personal protection. Even 10 years after the full coverage in LLIN no rebound effect was actually noticed in such natural conditions of life and plasmodial prevalence was even 2 times lower than before the implementation of vector control. Information gained were of great importance for the National Malaria Control program in term of nets replacement with 50% missing in 3 years underlining the need of “stronger” nets and community sensitization for the sustainability of positive results gained with LLIN.

Research on Electronic Expansion Valve Opening Mechanical Properties of Multi-Link Inverter Air-Con Based on Neural Network

2013 ◽  
Vol 644 ◽  
pp. 64-67
Author(s):  
Li Hui Guo ◽  
Wan Qiang Hu
Keyword(s):  
Neural Network ◽  
Mechanical Properties ◽  
Pid Controller ◽  
Control Mode ◽  
Expansion Valve ◽  
Valve Opening

The effects are unsatisfactory to adopt plain control mode for air-con refrigerating system with large lagging and nonlinearit features. The mechanical properties of electronic expansion valve are not sensible. In this article, BP-PID controller is adopted to control the system’s electronic expansion valve opening mechanical properties. The controller is designed. The experiment results show the controller is simple and effective, and well fulfills the users’ actual needs.

scholarly journals Polar tropospheric ozone depletion events observed in the International Geophysical Year of 1958

2006 ◽  
Vol 6 (11) ◽  
pp. 3303-3314 ◽  
Author(s):  
H. K. Roscoe ◽  
J. Roscoe
Keyword(s):  
Ozone Depletion ◽  
Surface Ozone ◽  
General Increase ◽  
Ozone Loss ◽  
International Geophysical Year ◽  
Obvious Reason ◽  
Frost Flowers ◽  
The Antarctic ◽  
International Geophysical

Abstract. The Royal Society expedition to Antarctica established a base at Halley Bay, in support of the International Geophysical Year of 1957–1958. Surface ozone was measured during 1958 only, using a prototype Brewer-Mast sonde. The envelope of maximum ozone was an annual cycle from 10 ppbv in January to 22 ppbv in August. These values are 35% less at the start of the year and 15% less at the end than modern values from Neumayer, also a coastal site. This may reflect a general increase in surface ozone since 1958 and differences in summer at the less windy site of Halley, or it may reflect ozone loss on the inlet together with long-term conditioning. There were short periods in September when ozone values decreased rapidly to near-zero, and some in August when ozone values were rapidly halved. Such ozone-loss episodes, catalysed by bromine compounds, became well-known in the Artic in the 1980s, and were observed more recently in the Antarctic. In 1958, very small ozone values were recorded for a week in midwinter during clear weather with light winds. The absence of similar midwinter reductions at Neumayer, or at Halley in the few measurements during 1987, means we must remain suspicious of these small values, but we can find no obvious reason to discount them. The dark reaction of ozone and seawater ice observed in the laboratory may be fast enough to explain them if the salinity and surface area of the ice is sufficiently amplified by frost flowers.

Vortex Tube Expansion Transcritical CO2 Heat Pump Cycle

2012 ◽  
Vol 190-191 ◽  
pp. 1340-1344 ◽  
Author(s):  
Ying Fu Liu ◽  
Chun Jing Geng ◽  
Guang Ya Jin
Keyword(s):  
Heat Pump ◽  
Ozone Depletion ◽  
System Performance ◽  
Vortex Tube ◽  
Outlet Temperature ◽  
Throttle Valve ◽  
Refrigerant Alternatives ◽  
Natural Refrigerant ◽  
Tube Expansion ◽  
Better Than

The application of natural refrigerant CO2 is of great significance to reduce the greenhouse effect and ozone depletion. Transcritical CO2 heat pump cycle is presently an important aspect of natural refrigerant alternatives research. In this paper, a vortex tube expansion transcritical CO2 heat pump cycle is established and compared to that of the transcritical CO2 refrigeration cycle with throttle valve. Thermodynamic analysis results indicate that the system performance of vortex tube expansion transcritical CO2 heat pump cycle is better than the transcritical CO2 heat pump cycle with throttle valve, and the COPh improvement is 5.8%~13.9% at given conditions. The gas-cooler outlet temperature has a great impact on the system performance, there is a higher COPh improvement when the cycle at lower evaporation temperature or higher gas-cooler outlet temperature.

Polar ozone depletion: A three-dimensional chemical modeling study of its long-term global impact

1996 ◽  
Vol 101 (D17) ◽  
pp. 22977-22989 ◽  
Author(s):  
Richard S. Eckman ◽  
William L. Grose ◽  
Richard E. Turner ◽  
W. Thomas Blackshear
Keyword(s):  
Ozone Depletion ◽  
Three Dimensional ◽  
Chemical Modeling ◽  
Global Impact ◽  
Polar Ozone ◽  
Modeling Study

scholarly journals Antarctic ozone depletion between 1960 and 1980 in observations and chemistry–climate model simulations

2016 ◽  
Vol 16 (24) ◽  
pp. 15619-15627 ◽  
Author(s):  
Ulrike Langematz ◽  
Franziska Schmidt ◽  
Markus Kunze ◽  
Gregory E. Bodeker ◽  
Peter Braesicke
Keyword(s):  
Ozone Depletion ◽  
Climate Model ◽  
Total Column Ozone ◽  
Antarctic Ozone ◽  
Climate Model Simulations ◽  
Ozone Depleting Substances ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column

Abstract. The year 1980 has often been used as a benchmark for the return of Antarctic ozone to conditions assumed to be unaffected by emissions of ozone-depleting substances (ODSs), implying that anthropogenic ozone depletion in Antarctica started around 1980. Here, the extent of anthropogenically driven Antarctic ozone depletion prior to 1980 is examined using output from transient chemistry–climate model (CCM) simulations from 1960 to 2000 with prescribed changes of ozone-depleting substance concentrations in conjunction with observations. A regression model is used to attribute CCM modelled and observed changes in Antarctic total column ozone to halogen-driven chemistry prior to 1980. Wintertime Antarctic ozone is strongly affected by dynamical processes that vary in amplitude from year to year and from model to model. However, when the dynamical and chemical impacts on ozone are separated, all models consistently show a long-term, halogen-induced negative trend in Antarctic ozone from 1960 to 1980. The anthropogenically driven ozone loss from 1960 to 1980 ranges between 26.4 ± 3.4 and 49.8 ± 6.2 % of the total anthropogenic ozone depletion from 1960 to 2000. An even stronger ozone decline of 56.4 ± 6.8 % was estimated from ozone observations. This analysis of the observations and simulations from 17 CCMs clarifies that while the return of Antarctic ozone to 1980 values remains a valid milestone, achieving that milestone is not indicative of full recovery of the Antarctic ozone layer from the effects of ODSs.

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