• Journal of Dental Anesthesia and Pain Medicine
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• v.20 no.3
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• pp.119-127
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• 2020

This study was conducted to determine how precooling reduces the subjective reported pain and objective pain and to evaluate the effectiveness of precooling the injection site before administration of local anesthesia in children. Electronic databases (PubMed, Ovid SP, Cochrane Central Register of Controlled Trials) were searched for publications from 1980 to 2020. Studies were screened for titles and abstracts, followed by full-text evaluation of included reports. Six studies were included in this systematic review. The primary outcome evaluated was the pain perception or the subjective pain reported by the child receiving the injection. The secondary outcome evaluated was objective pain evaluated in each study. Among 5 studies that evaluated child reported pain scores on a visual analogue scale (VAS), 4 studies reported lower scores in the precooling group and one study reported a higher VAS score in the precooling group than in children treated with 20% benzocaine topical anesthesia. Among 6 studies that evaluated the pain reaction of children by Sound Eye Motor (SEM) score, 4 studies reported a lower SEM score in the precooling group, one study reported no significant difference between the precooling and control groups, and one study reported higher SEM scores in the precooling group than in children treated with 20% benzocaine topical anesthesia. Within the limits of this systematic review, evidence suggests that precooling the injection site with ice can be an effective adjunct to topical anesthesia in reducing both subjective and objective pain during local anesthesia administration in children.

• Food Science and Preservation
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• v.3 no.1
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• pp.55-60
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• 1996

To obtain the basic data on precooling effects for establishment the suitable postharvest handling technique or method of keeping high quality of vegetalble corn, the sweet, supersweet and waxy corn, (Danok #2, Cocktail #86 and Chalok #1), being mainly consumed as vegetables in Korea, were precooled with ice or vacuum cooling method immediately after harvest. The vacuum cooling was the most effective for the field heat removal of vegetable corn. It took only 30 min. at 4 to 5 torr of cold chamber pressure of vacuum precooler to lower the corn temperature from 30 to 2$^{\circ}C$. The ice cooling was also thought to be a useful precooling method with relatively short cooling time of 6 hrs. The vegetable corn treated with vacuum or ice cooling showed low and stable respiration rates of 25.5 to 43.5 CO2 mg/kg/hr. when stored at 0∼2$^{\circ}C$ while the samples stored at room temperature (20∼25$^{\circ}C$) without precooling were as high as 64.1 to 245 CO, mg/kg/hr.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1093-1097
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• 2003

The aim of this study was to investigate the benefits of storing grapes through precooling, which is easier and more economical than the existing methods of storage. According to the analysis on the weight loss ratio, which is considered an important indicator of grape storage, the time at which the grapes reached 7% weight loss was prolonged by 5 to 10 days by the precooling method. Moreover, the percentage of abnormality on the 31st day of storage was at most 25% less in the precooled grapes than in the non-precooled grapes. In addition, the total bacterial count and the hardness of the precooled grapes were superior to those of the non-precooled grapes. Therefore, the precooling process markedly improved the commercial value of grapes.

• Food Science and Preservation
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• v.14 no.1
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• pp.109-112
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• 2007

Precooling and improved packing of mushrooms were investigated with a view to prolonging their freshness. Harvested mushrooms were precooled by forced air cooling and then packed in an EPS container. Mushrooms were transported to customers by insulated truck and stored at either $10^{\circ}C\;or\;25^{\circ}C$. Conventionally packed mushrooms in cartons were also examined as controls. Mushroom respiration rate slowly fell 2- to 3-fold upon precooling. Weight loss was decreased by precooling and the use of the insulated pack. Also, the L-value of the mushroom surface remained high with precooling, and mushroom elongation was less than in the control. Summer market life was extended to 3-4 days (from 1-2 days) by the improved distribution method.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.360-365
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• 2010

The effects of precooling treatments on the storability of chicon were investigated during modified atmosphere (MA) storage. The forced air cooling showed faster precooling rate that reduced the internal temperature of chicon to $2{\pm}1^{\circ}C$, and the precooling time of forced air cooling was 1/6 of room cooling. The half cooling time was 3 hr 21 min in room cooling and 1 hr 17 min in forced air cooling. Weight loss was less than 0.5% in all treatments both $5^{\circ}C$ and $10^{\circ}C$ MA storage and maintained higher in forced air cooling treatment. The concentration of carbon dioxide, oxygen, and ethylene of $50{\mu}m$ ceramic film packages were observed higher at $10^{\circ}C$ than $5^{\circ}C$. The precooling effect on respiration reduction was not shown at $5^{\circ}C$, but appeared that the gas concentration of precooling treatments showed less carbon dioxide and higher oxygen than non precooling treatment by 9 days after $10^{\circ}C$ storage. Ethylene concentration of precooling treatments showed lower than non precooling treatment until 3 days both $5^{\circ}C$ and $10^{\circ}C$ MA storage. Precooling showed the effect on maintaining visual quality of chicon both $5^{\circ}C$ and $10^{\circ}C$ MA storage. However, the forced air cooling that showed faster precooling rate did not appeared more precooling effect on the visual quality than room cooling because the fast air flow (6.0 m/sec) of forced air cooling hit directly on chicon outer leaves and might cause physical damage to chicon. Although the forced air cooling showed the effect on maintaining quality of chicon, but additional studies should be needed that investigated proper air flow rate and cooling box structure can prevent physical damage by air flow.

• Journal of the Korean Institute of Gas
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• v.15 no.3
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• pp.1-5
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• 2011

For the hydrogen liquefaction, the large amount of energy is consumed, because precooling, liquefaction and ortho/para conversion heats should be eliminated. In this paper the basic design and thermal analysis are carried out to reduce the energy consumption by using LNG cold energy for precooling process in hydrogen liquefaction processes. The LNG cold energy utilization for hydrogen precooling enables not only to get energy saving for liquefaction, but to recover the wasted cold energy to sea water at the LNG terminal. The results show that the energy saving rate for liquefaction using LNG cold energy is almost 75% of current industrial hydrogen liquefaction plant. The demand flow-rate of LNG is only 15T/D for 1T/D hydrogen liquefaction.

• International Journal of Air-Conditioning and Refrigeration
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• v.6
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• pp.124-135
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• 1998

A thermodynamic cycle analysis is performed for refrigerator-precooled Linde-Hampson hydrogen liquefiers, including catalysts for the ortho-to-para conversion. Three different configurations of the liquefying system, depending upon the method of the o-p conversion, are selected for the analysis. After some simplifying and justifiable assumptions are made, a general analysis program to predict the liquid yield and the figure of merit (FOM) is developed with incorporating the commercial computer code for the thermodynamic properties of hydrogen. The discussion is focused on the effect of the two primary design parameters - the precooling temperature and the high pressure of the cycle. When the precooling temperature is in a range between 45 and 60 K, the optimal high pressure for the maximal liquid yield is found to be about 100 to 140 bar, regardless of the ortho-to-para conversion. However, the FOM can be maximized at slightly lower high pressures, 75 to 130 bar. It is concluded that the good performance of the precooling refrigerator is significant in the liquefiers, because at low precooling temperatures high values of the liquid yield and the FOM can be achieved without compression of gas to a very high pressure.

• Journal of the Korean Institute of Gas
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• v.24 no.4
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• pp.56-61
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• 2020

For the hydrogen liquefaction, the large amount of energy is consumed, due to precooling, liquefaction and o-p conversion processes. The aim of this work is to improve the performance of hydrogen liquefaction process by introducing the new energy saving processes, that are the liquid nitrogen precooling process by using LNG cold energy, and the new design of cold box insulation using cold air circulation. The results show that the indirect use of LNG cold energy in precooling process enables not only to get energy saving, but to make safer operation of liquefaction plant. In new cold box, the energy loss of equipments could be reduced by nearly 35%~50% compared to the present perlite insulation, if insulation structure is organised as 3mm steel wall/20cm PUF/5cm air/20cm PUF/equipment. Additionally the equipments installed in cold box can get cooling effect, if the temperature is higher than the temperature of cold air. The application of this results can gives to increase the liquid yield of about 50% substantially in industrial hydrogen liquefaction plant.

• Food Science and Preservation
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• v.4 no.2
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• pp.115-122
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• 1997

This experiment was hocused on the improvement of postharvest management of fresh shiitake to increase the marketing duration. the respiration rate of fresh shiitake at 2$0^{\circ}C$ was ranged from 395mg to 551mg CO2/kg/hr depending on the cultural condition. The rapid precooling is considered as one of the most important postharsvest management to remain shiitake quality. The optimum temperature for precooling and storage was -3$^{\circ}C$ because the occurrence of physical damage on frozen tissue at below -5$^{\circ}C$. Frozen storage at -3$^{\circ}C$ had benefits to minimize weight loss, browning induction at gill tissue and consumption of stored materials where as storage at $0^{\circ}C$ appeared not to be adequite for the extension of marking duration. Frozen shiitake was succesefully thawed when exposed to RH 40-50% at below 1$0^{\circ}C$.

• Transactions of the Korean hydrogen and new energy society
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• v.9 no.2
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• pp.53-64
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• 1998

Thermal analysis on a Linde-Hampson hydrogen liquefaction system using cryogenic refrigerators as precooling has been carried out. Three commercially available models of cryogenic refrigerators, such as CTI l020CP, CVI CGR009 and CVI CGR011, are considered in the performance analysis. The effect of ortho-para conversion process during hydrogen liquefaction is also studied in detail. The results obtained indicate that the optimal hydrogen mass flow rate and the optimal compressed pressure exist for the maximum hydrogen liquefaction rate. The optimal compressed pressure is increased in the range of 80 - 120 bar with an increase in the hydrogen mass flow rate. It is also found that better performance could be obtained with a cryogenic refrigerator, which produces high cooling capacity at precooling temperature in the range of 80 - 100 K.