Eungchan Lee

Numerical Study on the Distribution Characteristics of Aluminum Plate-Fin Heat Exchangers According to the Distributor Aspect Ratio

Aluminum plate-fin heat exchangers (ALPHEs) are widely used in petroleum and gas-treated processes. The performance of the ALPHE is strongly dependent on the distribution characteristics of the header and the distributors of each fluid. In this paper, we define the aspect ratio in the side-entry type distributor and analyze the distribution characteristics using CFD-based numerical methods. The phenomena of velocity deviation and distribution with the aspect ratio and the inlet Reynolds number were analyzed by applying relative and absolute maldistribution parameters, and an optimum aspect ratio with the inlet Reynolds number was presented.

Performance Characteristics of Plate Heat Exchangers with Various Geometric Design Parameters

Key Words: PlateHeatExchanger(판형열교환기),HeatTransfer(열전달),PressureDrop(압력강하),DesignParameter(설계변수),Correlation(상관관계)초록: 판형열교환기는높은효율로인하여다양한산업분야에사용되고있으며, 판형열교환기의성능특성을파악하기위해많은연구가이루어졌다.하지만세브론각을제외한판형열교환기의기구적설계변수에따른성능특성파악은상대적으로많이부족한실정이다. 본연구는판형열교환기의기구적설계변수에따른열전달및압력강하성능특성을파악하기위해서세브론각, 전열판골깊이, 전열판골길이, 전열판개수등을변화시키며실험을수행하였다. 실험결과를바탕으로판형열교환기의다양한기구적설계변수를반영한열전달및압력강하성능특성상관식을제안하였다. 실험데이터와제안된판형열교환기상관식을이용해예측된데이터를비교한결과약95%이상의데이터가±10%오차범위내에존재함을알수있었다.Abstract: Plate heat exchangers have been widely used in many industrial applications because of theircompactness and high efficiency. Even though plate heat exchangers have been investigated extensively,studies on the effects of geometric parameters other than the chevron angle are very limited in the openliterature. In this study, the effects of the chevron angle, corrugation length, corrugation depth, and thenumber of plates on the heat transfer and pressure drop characteristics of plate heat exchangers wereinvestigated experimentally. Based on the experimental results, empirical correlations were proposed. Morethan 95% of the predictions made based on the correlations had relative deviations of less than ±10% whencomparedwiththemeasureddata.

The Fouling Characteristics of Plate Heat Exchangers with Geometric and Operating Parameters

Abstract The plate heat exchanger has been widely used in water heating systems due to high efficiency, simple structure,and easy maintenance. However, the studies on the effects of fouling on the heat transfer performance under various operationand maintenance conditions are very limited in the open literature. The objective of this study is to investigate the effects of fouling with calcium carbonate (CaCO 3 ) on the heat transfer characteristics of the plate heat exchanger under variousoperating and geometric conditions. The heat transfer coefficient and pressure drop in the plate heat exchangers were measuredunder accelerated fouling conditions with CaCO 3 by varying geometric and operational parameters. The fouling resistance increased with the decrease in the flow rate, and the increase in the chevron angle and the concentration. Key words Calcium carbonate(탄산칼슘), Fouling(파울링), Heating and service hot water(난방 및 급탕), Plate heat exchanger(판형열교환기)†Corresponding author, E-mail: yongckim@korea.ac.kr

Parametric Analysis of an Aluminium Plate-Fin Heat Exchanger (ALPHE) for LNG-FPSO

A nitrogen double expander cycle has been widely used for liquefaction of natural gas in LNG-FPSO (Floating Production, Storage, and Offloading). An aluminum plate-fin heat exchanger (ALPHE) is usually adopted in the liquefaction cycle. In general, the ALPHE has a very large heat transfer surface area per unit volume. This surface area consists of primary and secondary (finned) surfaces. Even taking into account fin efficiency of the secondary surface, the effective surface area per unit volume can be typically five times greater than that of a shell-and-tube heat exchanger. Various types of fin are available in ALPHE and the fin type should be selected properly to optimize the performance. For example, serrated, wavy and perforated fin are particularly suitable for gas streams. The selection and design of the layer arrangement and effective length of each stream are very important design parameters for ALPHE. In this paper, to optimize the design of ALPHE, the effects of the design parameters on the performance of ALPHE were studied using a simulation method. The properties of nitrogen and natural gas were calculated from proper equations of state. Because the performance of ALPHE is mainly influenced by the fin type, fin frequency, fin height, fin thickness, and layer arrangement, the effects of the geometric design parameters on the performance of ALPHE were studied, and the optimum design conditions were suggested in this paper.Copyright

Cooling and Heating Performances of a CO2 Heat Pump with the Variations of Operating Conditions

Abstract Since operating conditions are significantly different for heating and cooling mode operations in a CO 2 heat pump system, it is difficult to optimize the performance of the CO 2 cycle. In addition, the performance of a CO 2 heat pump is very sensitive to outdoor temperature and gascooler pressure. In this study, the cooling and heating performances of a variable speed CO 2 heat pump with a twin-rotary compressor were measured and analyzed with the variations of EEV opening and compressor frequency. As a result, the cooling and heating COPs were 2.3 and 3.0, respectively, when the EEV opening was 22%. When the optimal EEV openings for heating and cooling were 28% and 16%, the cooling and heating COPs increased by 3.3% and 3.9%, respectively, over the COPs at the EEV opening of 22%. Beside, the heating performance was more sensitive to EEV opening than the cooling performance. As the compressor speed decreased by 5 Hz, the cooling COP increased by 2%, while the heating COP decreased by 8%.