Spent nuclear fuel (SNF) characterization is important in terms of nuclear safety and safeguards. Regardless of whether SNF is waste or energy resource, the International Atomic Energy Agency (IAEA) Specific Safety Guide-15 states that the storage requirements of SNF comply with IAEA General Safety Requirement Part 5 (GSR Part 5) for predisposal management of radioactive waste. GSR Part 5 requires a classifying and characterizing of radioactive waste at various steps of predisposal management. Accordingly, SNF fuel should be stored/handled as accurately characterized in the storage stage before permanent disposal. Appropriate characterization methods must exist to meet the above requirements. The characterization of SNF is basically performed through destructive analysis/non-destructive analysis in addition to the calculation based on the reactor operation history. Burnup, Initial enrichment, and Cooling time (BIC) are the primary identification targets for SNF fuel characterization, and the analysis mainly uses the correlation identified between the BIC set and the other SNF characteristics (e.g., Burnup - neutron emission rate) for characterizing. So further identification of the correlation among SNF characteristics will be the basis for proposing a new analysis method. Therefore, we aimed to simulate a SNF assembly with varying burnup, initial enrichment, and cooling time, then correlate other SNF properties with BIC sets, and identify correlations available for SNF characterization. In this study, the ‘CE 16×16’ type assembly was simulated using the SCALEORIGAMI code by changing the BIC set, and decay heat, radiation emission characteristics, and nuclide inventory of the assembly were calculated. After that, it was analyzed how these characteristics change according to the change in the BIC set. This study is expected to be the basic data for proposing new method for characterizing the SNF assembly of PWR.

In the present study, the experimental study was conducted using a multi-calorie meter, to investigate the cooling performance and cycle operation changes of the multi-heat pump (3 indoor units) for the low outside temperature in summer. The test temperature condition was the low cooling temperature, and the normal performance and dynamic behavior of 3 rooms, 2 rooms, and 1 room were measured to understand the operating characteristics of seven 7 indoor unit combinations. As a result of the experiment, the cooling capacity and COP of the multi-heat pump at low cooling temperature were about 10% and 6% higher than those of the cooling standard temperature. In addition, the dynamic behavior of the indoor units of 3 and 2 rooms was observed differently due to the load difference according to the indoor unit combinations and the non-uniformity of the refrigerant amount. And, when starting the heat pump, the compressor had a maximum peak value and stabilized by repeating the decrease and increase for each indoor unit combination.

Test of the operating characteristics and energy saving performance of a container cooling system that reduces the operating energy of a refrigeration system using a loop thermosyphon heat exchanger that removes heat by temperature difference between outdoor and indoor was performed. As a result of the experiments, when the loop thermosyphon and the refrigeration system were operated simultaneously, the refrigeration system operated intermittently by reducing the heat load. As the temperature difference between indoor and outdoor increased, the operating time of the refrigeration system decreased and the energy efficiency rate increased. Energy efficiency rate showed a tendency to increase with increasing temperature difference, and the predicted correlation of energy efficiency rate using the performance of the loop thermosyphon heat exchanger and the refrigeration system was relatively consistent with the experimental value.

In the present study, to investigate the cooling characteristics of the multi-heat pump with 3 indoor units, 7 indoor unit combinations and 3 setting temperatures are selected to study the cooling characteristics during steady-state operation. The cooling capacity, power consumption, COP, compressor high and low pressure of the heat pump are tested under the cooling standard temperature conditions using an air enthalpy multi-calorimeter. The experimental results show that, except for an operation with an indoor unit capacity of 30% or less, the cooling capacity, power consumption, and compressor operation frequency increase as the capacity of the indoor unit increases and the setting temperature of the indoor unit decreases. COP increases or decreases according to the compressor frequency, and is the best at 50-80% capacity of the indoor unit. As the compressor frequency increases, the compressor outlet pressure increases by about 30%.

In order to experimentally investigate the operation characteristics of the multi-heat pump with 3 indoor units, the dynamic characteristics of the cooling cycle is studied using the psychrometric multi-calorimeter. The compressor of the heat pump is the scroll inverter type, and since 3 indoor units operate cooling at the same time, it is operated at 100% full load. In particular, 3 types of indoor unit temperatures (20, 24, 26°C) are selected to understand the operation process of the multi-heat pump by the setting temperature. From this experiment, the compressor controls the EEV opening for each indoor unit while varying the frequency according to the initial start, transient, and steady operation. In addition, as the setting temperature increases in the steady range, the frequency of the compressor and the average opening degree of the EEV decrease.

본 연구는 권취식 측창을 갖는 아치형 단동 플라스틱 온실 내 강제환기장치 설치 및 운용, 환기 성능 개선방안 등을 제안 하기 위해 온실 내부에 유동팬과 배기팬을 설치하여 강제환기 장치 사용에 따른 온실 내부기온 강하 특성을 정량적으로 조 사하였다. 시험은 3가지 환기 조건(측창, 측창+순환팬, 측창+ 순환팬+배기팬)에서 수행되었다. 각 조건 데이터로거를 이용 하여 환기 시작과 동시에 온실 내외부 기온 및 외부환경 변화 를 측정·기록하였고, 환기 방식별 기온차 변화의 평균값으로 부터 정규기온차를 계산하여 기온 강하 효과를 비교하였다. 오전(11:00－12:00)에는 환기 방식에 상관없이 환기 초반 정 규기온차가 일시적으로 증가했다가 감소하는 것으로 나타났 다. 강제환기장치가 더 많이 사용될수록 최대 정규기온차는 1.158에서 1.037로 감소하였고 최대 정규기온차에 도달하는 시간도 340초에서 110초로 단축되었다. 강제환기장치의 사 용은 정규기온차가 0.8까지 감소하는데 소요된 시간을 1,030 초에서 550초로, 0.6까지는 1,610초에서 915초로, 0.4까지는 2,315초에서 1,360초로, 자연환기의 약 60% 수준으로 감소 시켰다. 오후(14:00－15:00)에는 정규기온차의 증가가 관측되지 않았지만, 환기 시작과 동시에 기온차가 감소하기 시작 했다. 또한 강제환기장치가 더 많이 사용될수록 정규기온차 가 0.8까지 내려가는 시간을 560초에서 345초로, 0.6까지는 825초에서 540초로, 0.4까지는 560초에서 345초로, 약 70% 수준으로 감소시켰다. 따라서, 보다 효과적이고 경제적인 환 기를 위해 강제환기장치는 오전과 같이 열부하가 높은 환경에 서 적극적으로 사용하는 것이 바람직하다고 판단된다.

본 연구는 냉방이 가능한 반밀폐형온실과 일반 플라스틱온 실에서의 정식 후 고온 스트레스가 파프리카에 미치는 영향 구명을 위해 수행하였다. 지열과 팬앤패드를 활용하여 냉방이 가능한 반밀폐형온실의 파프리카는 냉방이 되지 않는 3중 플라스틱 하우스의 파프리카보다 유의적으로 높은 광합성 속도를 보여 주었다. 플라스틱 하우스의 파프리카가 고온 스트레스에 의해 광합성 속도가 느려지는 것을 제시하고 있다. 초장은 반밀폐형온실이 13cm 더 높게 증가하였으며, 엽면적은 이식 후 2주차까지 생장 속도가 비슷하였으나 3주차 경과 시 반밀폐형온실이 플라스틱온실보다 47% 높은 차이를 보였다. 착과 수는 반밀폐형 온실 10.6개/주, 플라스틱온실 4.6개/주가 착과하여 플라스틱 온실 대비 반밀폐형온실이 130% 높게 착과하였다. 과중 또한 반밀폐형온실과 플라스틱온실이 각각 566.7g/plant와 387g/plant으로 46% 차이를 나타냈다. 이상의 결과로 냉방이 가능한 반밀폐형온실에서 파프리카를 재배할 경우 일반 플라스틱온실보다 광합성과 생육이 양호하였음을 확인할 수 있었다. 따라서, 반밀폐형온실의 냉방 효율을 위한 요소기술을 일반 플리스틱온실에 적용하여 여름철 고온기를 극복한다면 수확량 및 품질 향상을 통한 농가소득 증대가 가능해질 것으로 기대된다.

In this study, we investigated the effects of cooling rate during storage on spring kimchi cabbage from an economic perspective. For long-term storage, kimchi cabbage (KC) should be maintained at a low temperature immediately after harvest; however, a sudden change in temperature during storage may lead to chilling injury in KC. The optimal cooling rate is important for the long-term storage of KC. To identify the optimal cooling rate, KC was cooled at different cooling rates (1oC, 2oC, 4oC, 6oC, 8oC, and 24 oC/day), and then stored at 1oC for 90 days. Thereafter, weight, trimming, total loss, pH, free sugar content, and total bacterial count changes were measured. Spring KC stored at the cooling rate of 6 oC/day presented a lower total loss and better sensory properties than KC stored at other cooling rates; thus, 6 oC/day is an appropriate cooling rate for long-term storage of KC.

The effect of flow direction on heat transfer in water cooling channel of lithium-ion battery is numerically investigated. Battery Design StudioⓇ software is used for modeling electro-chemical heat generation in the battery and the conjugated heat transfer is analyzed with the commercial package STAR-CCM+. The result shows that the maximum temperature and temperature difference of battery with Type 1 are the lowest because the heat transfer in the entrance region near the electrode is enhanced. As the inlet velocity is increased, the maximum temperature and temperature difference of battery decreases but the pressure loss increases. The pressure loss in Type 2 channel is the lowest due to the shortest channel length, while the pressure loss with Type 3 or 4 channel is the highest because of the longest channel length. Considering heat transfer performance and pressure loss, Type 1 is the best cooling channel.

The purpose of this study is to analyze the temperature and heat resistance distribution, which is a criterion for evaluating the cooling performance, by using computer simulation of the cooling system combined with the CPU of the individual highest heat generation section, and use it as important data for the heat sink design. Using a single material of Al 6063-T5, which is an integral part of the desktop, fan and heat sink, fins and base, the analysis was carried out with various fin numbers, thicknesses, pitches and shapes of heat sinks. Ambient temperature, 25°C, heat source, 130W and cooling fan speed, 2500 rpm (50CFM) were used as boundary conditions, and heat transfer characteristics regarding temperature distribution and heat resistance were investigated using ANSYS Icepak. As a result, it has been found that as the number of fins of heat sink increases, the heat dissipation area increases to decrease heat resistance, and as the distance between each fin decreases, the ventilation resistance increases to decrease the flow intensity of the cooling air in contact with the heat dissipation area. The sunburst array also exhibits better heat transfer characteristics by obtaining a lower distribution of heat resistance with a cooling effect of about 10°C than the one-way basic array.

Experiments were conducted on the operating characteristics and performance of various types of working fluid, filling amount and heat flow rate of a loop thermosyphon for cooling ESS battery container. As results of performance test on various working fluids, HFE-7100 and R-134a as a working fluids showed unstable operating and low performance due to vapor pressure drop, and performance was improved by increasing the number of vapor lines for reducing a pressure drop. In this study, n-pentane was more stable and showed better thermal performance among various working fluids.

In this study, heat exchangers used in data center and building air-conditioners were tested according to the type of heat exchangers to select them for commercial use. The experiment was performed three samples, one micro channel heat exchanger, the same volume oval coil and the same performance oval coil. The experiment conducted under actual operation conditions in the data center and building. Micro-channel heat exchanger has lower air side pressure drop and higher capacity per volume than oval coil. It may be advantageous when the installation small space or the little design static pressure in the fan, such as in-row systems or CRAC installed in data center.

In this study, the change of cooling water temperature (72, 85, 95 ℃) and engine speed (1,800, 2,000, 2,200, 2,400rpm) were experimentally investigated to confirm the operation performance characteristics of auxiliary engine for refrigeration unit. The experimental setup consisted of fuel consumption meter, power meter, and heat transfer unit. The operation performances such as BSFC, exhaust temperature, power generation, and engine efficiency of the auxiliary engine showed similar characteristics in the present experimental range, according to the change of cooling water temperatures and rpms. As the torque increased, the BSFC decreased significantly and the exhaust temperature increased. The power generation increased linearly and the efficiency was insignificant at more than 40 Nm torque.

In this study, the cooling and heating amount, temperature, flow rate of turbine type heat meter for water source heat-pump system were experimentally investigated at the standard operating conditions. The obtained cooling and heating capacity from the heat meter were deviated within 5.0%, 3.8% comparing with the precise values calculated from an accredited test facility. Even though the accumulated cooling and heating amount values of the heat meter had a small difference comparing with the precise values, the temperatures of heat meter showed greatly different values comparing with the precise temperature. Therefore, it is highly recommended to develop the heat meter which is appropriate for the water source heat pump systems.

Cooling operation characteristics of multi-A/C(air conditioner)s were experimentally investigated for combination of indoor units (A+B, A+C, B+C) and operating conditions (standard, overload, low temperature and low temperature freezing). The operating data and performance of the air conditioner were measured using a multi-calorimeter. We also observed compressor frequency and pressure variations. From the experimental results, it was found that the cooling performance and the operating characteristics depend on operation combination of indoor units, in the case of 2 room simultaneous operation. In the four types of cooling tests, the cooling capacity and COP of the 3 room simultaneous operation and 2 room simultaneous operation were similar. Through this experimental study, data on the simultaneous operation characteristics of 2 room simultaneous operation according to the changes of indoor and outdoor temperature of four kinds were obtained.

The cooling operating characteristics of the 3 room air conditioner are experimentally investigated for the number of the indoor units (A, B, C) and the operating conditions (standard, overload) under the cooling operation. The cooling capacity and COP were calculated using a multi-type calorimeter. Also, EEV opening, compressor frequency, and superheat degree were obtained when the compressor started. From the experimental results, we can see that the performance and operation characteristics of the air conditioner depend on the indoor unit operation method. In case of simultaneous and single operation, the cooling overload performance was measured lower than the standard condition. Also, in the overload operation, the power consumption of the compressor was greatly increased and the COP was also decreased.

Currently, the cutting oil supply device is not equipped to cool the cutting oil. Therefore, additional cooling device should be connected to cool the cutting oil. This has the disadvantage of increasing the size of the device and reducing its cooling capability. To overcome these shortcomings, cooling coils are applied to the outside of the cutting oil filtering device to develop a heat exchanger filter for simultaneous coolant filtering and cooling to improve the compactness of the cutting oil supply device and cooling capability of the cutting oil. For the development of heat exchanger filter, flow and heat transfer analysis were performed. Due to the small heat transfer area of 10 cooling coils, less heat exchange occurred. In the 20 cooling coils, the coolant cooling coils prevented smooth flow of the cooling oil in the heat exchanger filter. The cooling efficiency of the 15 cooling coils were best, and the cooling temperature decreased non-linearly as the supply flow rate of the cutting oil increased.