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In this study, the comprehensive study of the performance investigation of Solid Desiccant Based Dehumidification (SDBD) system which involves the desiccant selection and desiccant coating with metallic heat exchanger was conducted at the mild humid conditions which represent the humid air conditions in summer, South Korea. The water uptake capacity of three different solid desiccants was investigated to find the proper solid desiccant in the SDBD system under the given operating conditions. Among the three different solid desiccants, the aluminum fumarate based metal organic frameworks (MOFs) was selected as the best solid desiccant for SDBD system and it has the maximum water uptake capacity around 0.398 g·g−1 for given operating conditions. The aluminum fumarate based metal organic frame works (MOFs) was coated on the metallic surface of heat exchanger by current developed coating method and the desiccant and binder solution is consistent of 10% of binder and solvent mixture and 90% of aluminum fumarate based MOFs. As a result, the increase of coating thickness from 0.05 mm to 0.2 mm and operating time from 150 s to 300 s can achieve the 113% and 131% of dehumidification performance enhancement in average, respectively. Remarkably, over 160% improvement of dehumidification performance in average can be achieved by the decrease of space velocity from 13 s−1 to 5.2 s−1.

In this study, the performance evaluation of an adsorption chiller (AD) system with three different adsorbents—silica-gel, aluminum fumarate, and FAM-Z01—was conducted to investigate the effects of adsorption isotherms and physical properties on the system’s performance. In addition, the performance evaluation of the AD system for a low inlet hot-water temperature of 60 °C was performed to estimate the performance of the system when operated by low quality waste heat or sustainable energy sources. For the simulation work, a two-bed type AD system is considered, and silica-gel, metal organic frameworks (MOFs), and ferro-aluminophosphate (FAPO, FAM-Z01) were employed as adsorbents. The simulation results were well matched with the laboratory-scale experimental results and the maximum coefficient of performance (COP) difference was 7%. The cooling capacity and COP of the AD system were investigated at different operating conditions to discuss the influences of the adsorbents on the system performance. Through this study, the excellence of the adsorbent, which has an S-shaped isotherm graph, was presented. In addition, the influences of the physical properties of the adsorbent were also discussed with reference to the system performance. Among the three different adsorbents employed in the AD system, the FAM-Z01 shows the best performance at inlet hot water temperature of 60 °C, which can be obtained from waste heat or sustainable energy, where the cooling capacity and COP were 5.13 kW and 0.47, respectively.

To build an eco-friendly and sustainable energy ecosystem, research pertaining to absorption systems that can utilize waste heat from various industries is garnering attention. Among the elements of the absorption system, the phenomenon of heat and mass transfer in the absorber is complicated, and the predictive performance of existing absorber correlations is insufficient for universal use. Artificial neural network models are being considered as alternatives to existing methods in various fields. However, there is still a need for conventional correlations that allow easy analysis of physical relationships. In this study, rather than developing a model to classify or predict with an artificial neural network, it is used to analyze the collected experimental data. This method is expected to contribute to the easier development of more accurate correlations. Using the learned artificial neural network model, off-trend data organization, key parameter determination, and trend investigation for each parameter are performed. Based on the results of this investigation, a universally usable correlation for predicting absorber heat transfer is developed. The correlation, which can integrate the experimental data of nine published papers, is reviewed; it is demonstrated that the investigation results are consistent with the experimental data, with an error of approximately 22%.

Waste heat is a form of renewable energy discarded into the atmosphere. Waste heat-driven absorption systems (i.e., heat pumps and refrigeration systems) have attracted attention as district heating and cooling systems. This study proposes a waste heat-driven hybrid lithium bromide-water absorption system for the simultaneous generation of available steam and refrigeration effects. The proposed system is a form of the combined closed thermal cycle between the sub-heat pump and the sub-refrigeration system. It shares a generator and condenser, which allows the system to be more compact and flexible. We first present a description of the proposed system, designed for a cooling capacity of 350 kW with a steam generation rate of 200 kg/h. Our preliminary study proposed a pilot-scale system to clarify the flexible and simultaneous control means of the heating and cooling capacities by partially distributing the flow rate of the LiBr solution entering each sub-cycle. In addition to the results from the preliminary study, the present work examined the effect of part-load conditions on the operating parameters of the hybrid absorption system. The results showed that the coefficient of performances of sub-refrigeration and sub-heat pump cycle were approximately 0.787 and 0.658, respectively, and as a result, the total coefficient of performance of 0.463 was achieved. The theoretical model was validated by the experimental data, and the payback analysis was suggested to assure the economic validity of the proposed system. It was noted that the proposed hybrid absorption system demanded high initial facility cost than the comparison groups, but a payback of 2.79 and 2.36 years was evaluated because of the use of low-grade energy.

The applications of electronic expansion valves in high temperature heat pump have increased rapidly. However, correlations for predicting R245fa mass flow rate through electronic expansion valves in high temperature heat pump are very limited in open literatures. In this study, mass flow rate characteristics of R245fa refrigerant flowing through electronic expansion valves with different operational conditions are studied experimentally, and empirical correlations are proposed based on the experimental data. The results reveal that the mass flow rate increases with increasing opening degree, condensation temperature, subcooling, and orifice diameter. Based on a modified single phase orifice equation, two empirical correlations are proposed by using the power-law correlation and the polynomial fit correlation, and over 92% of the predicted data deviate from the experimental data within ±15%.

The absorber is one of the most important components in the LiBr-water absorption heat transformer (AHT) because it has the largest heat transfer area, and its performance significantly influences the overall system efficiency. Nevertheless, studies on absorbers used at the high-pressure level have not progressed. In this study, the horizontal tube falling film absorbers were constructed by introducing three types of heat transfer tubes (copper bare, copper-nickel bare, copper-nickel floral). The combined effects of the tube structure and material on the heat transfer performance of the absorber were experimentally investigated under the operating conditions of the single-stage AHTs. The experimental results showed that the film Reynolds number of 50 was optimal for the absorbers used in this study. At that point, the overall heat transfer coefficients of the copper bare tube, the copper-nickel bare tube, and the copper-nickel floral tube were 1,484, 1,448, and 1,299 W/m2 K, respectively. In addition, the heat transfer performance of the bare-type tubes was superior to that of the floral tube, except the under the low film Reynolds number. The empirical correlations of the Nusselt number for three types of heat transfer tubes were derived based on the experimental results and were predicted the data within the standard errors of 3.79–5.57 %.

In this paper, heat transfer characteristics of fin-tube heat exchanger and primary surface heat exchanger (PSHE) used in waste heat recovery were investigated experimentally. The flow in the fin-tube heat exchanger is cross flow and in PSHE counter flow. The variations of friction factor and Colburn j factor with air mass flow rate, and Nu number with Re number are presented. Various comparison methods are used to evaluate heat transfer performance, and the results show that the heat transfer rate of the PSHE is on average 17.3% larger than that of fin-tube heat exchanger when air mass flow rate is ranging from 1.24 to 3.45 kg/min. However, the PSHE causes higher pressure drop, and the fin-tube heat exchanger has a wider application range which leads to a 31.7% higher value of maximum heat transfer rate compared to that of the PSHE. Besides, under the same fan power per unit frontal surface, a higher heat transfer rate value is given in the fin-tube heat exchanger.

A numerical analysis was conducted to examine the effect of a coating technique on adsorption cooling system (ACS) performance compared to a fully-filled grain configuration. The main interest was the effect of coating thickness, binder and cycle time for adsorption cooling applications. Validation of the numerical model was confirmed by comparison with experiment. The coating configuration resulted in a larger interfacial area to open space and also a shorter length of vapor flow path compared to the fully-filled configuration, which enhanced the vapor flow and resulted in higher performance. The optimal coating thickness was found to be 0.2–0.5 mm. A short cycle time was enough for the coating configuration, which improved system performance. For example, at coating thickness t = 0.2 mm, a 34.17% enhancement in specific cooling power (SCP) was achieved with a shorter cycle time of 480 s rather than 840 s, with the penalty of 9.87% decrease in coefficient of performance (COP). The coating technique with reduced cycle time is a good design approach for adsorption cooling systems. The binder had a negative effect on system performance, but the coating technique had clear advantages compared to the fully-filled configuration, and there was no other way of binding the adsorbent particles together. Thus, it is recommended that the binder content be kept as small as it can be.

This paper investigates the characteristics of ferroaluminophosphate (FAM-Z01) compared to various types of conventional silica gels in the performance of an adsorption bed. FAM-Z01 has high potential to replace silica gel due to some key advantages, including a low heating temperature and high adsorption rate resulting from its S-shaped isotherm. We conducted a performance simulation on a fin-tube type adsorption bed with FAM-Z01/water and silica gel/water working pairs and compared the results in terms of coefficient of performance (COP) and specific cooling power (SCP). In the partial pressure range of typical operating condition for silica gels, there was no advantage with FAM-Z01. However, in the partial pressure range of 0.14

In this study, the performance characteristics of a high temperature heat pump dryer that is able to raise the air temperature up to 80℃ by using waste heat as heat source were investigated numerically. The main components of the heat pump dryer were modeling as a compressor, condenser, evaporator and expansion device, and R245fa was selected as refrigerant. Experiments were also conducted to validate the numerical data. As a result, when the evaporator air inlet temperature increased from 50℃ to 65℃, the numerical results of the hot air temperature at outlet and heat pump COP were about 8~11% and 5~8% higher than that of experimental ones, respectively. Key Words ：Dryer, Heat Pump, R245fa, Waste Heat Recovery *†권오경(교신저자) : 한국생산기술연구원 열유체시스템그룹E-mail : kwonok@kitech.re.kr, Tel : 041-589-8528 *배경진, 차동안 : 한국생산기술연구원 열유체시스템그룹*†Oh-Kyung Kwon(corresponding author) : Thermal & FluidSystem Group, Korea Institute of Industrial Technology.E-mail : kwonok@kitech.re.kr, Tel : 041-589-8528 *Kyung-Jin Bae, Dong-An Cha : Korea Institute of Industrial Technology.

The objectives of this paper are to develop correlations between heat transfer and pressure drop for oval finned-tube heat exchanger with large diameters (larger than 20 mm) used in a textile machine dryer. Numerical tests using ANSYS CFX are performed for four different parameters; tube size, fin pitch, transverse tube pitch and longitudinal tube pitch. The numerical results showed that the Nusselt number and the friction factor are in a range of −16.2 ~ +3.1 to −7.7 ~ +3.9 %, respectively, compared with experimental results. It was found that the Nusselt number linearly increased with increasing Reynolds number, but the friction factor slightly decreased with increasing Reynolds number. It was also found that the variation of longitudinal tube pitch has little effect on the Nusselt number and friction factor than other parameters (below 2.0 and 2.5 %, respectively). This study proposed a new Nusselt number and friction factor correlation of the oval finned-tube heat exchanger with large diameters for textile machine dryer.

The formation and growth of frost in air source refrigeration systems cause degradation of the system’s performance. Super-hydrophobic technology can delay frost growth and it has received much attention. However, only a limited number of studies have investigated the effects of super-hydrophobic surfaces on frost growth. This study therefore investigated the effects of surface characteristics on frost retardation in heat exchangers with various fin pitches. Heat exchangers with bare, hydrophobic, and super-hydrophobic surfaces were tested, and their frost retardation capabilities were evaluated by comparing the time taken for the air flow passage to be blocked. Hydrophobic and super-hydrophobic surfaces delayed the time by an average of 14.4% and 42.0%, respectively, compared to bare surfaces. The effect of surface characteristics on the heat transfer rate and pressure drop of the heat exchanger was also evaluated. Super-hydrophobic surfaces reduced the decrease in the heat transfer rate and increased the pressure drop by 14.4% and 470%, respectively, compared to bare surfaces. For a system that involves repeated frosting and defrosting, it is estimated that the super-hydrophobic surface can increase the average heat transfer rate by approximately 4.8% more than a bare surface.

The objective of this paper is to provide design data of fin-tube heat exchanger which have a large diameter ovaltube for dryer application. In this study, the heat transfer and pressure drop performance characteristics of the fin-tube heatexchanger were compared with Dittus-Boelter and a new correlation equation using Wilson plot method. The simulationresults based on section by section method were compared with experimental results. These results showed that a new correlationequation using Wilson plot method provided better prediction, about 3 to 12%, than the Dittus-Boelter equation, from theexperiment comparison. Also, the pressure drop of simulation results showed much more deviation with the experimentalresults.. Key words Fin-tube heat exchanger(핀-관 열교환기), Heat transfer coefficient(열전달계수), Oval tube(타원관), Prssure drop(압력강하)†Corresponding author, E-mail: kwonok@kitech.re.kr 기호설명 A ： 면적 [ ㎡ ] C ： 열용량 [W/k] D ： 직경 [m] D h ： 열교환기 수력직경 [m] F p ： 핀간격 [m] h ： 열전달계수 [W/ ㎡․ K] k

The objective of this study is to investigate the influence of the cooling performance for a water-to-water ground source heat pump (GSHP) by using the counter flow and parallel flow methods. The GSHP uses R-410A as a refrigerant, and its main components are a scroll compressor, plate heat exchangers as a condenser, an evaporator, a thermostatic expansion valve, a receiver, and an inverter. Based on our modeling results, the heat transfer rate of the counter flow evaporator is higher than that of the parallel flow evaporator for a heat exchanger length greater than 0.42 m. The evaporator length of the GSHP used in this study was set to over 0.5 m. The performance of the water-to-water GSHP was measured by varying the compressor speed and source-side entering water temperature (EWT). The cooling capacity of the GSHP increased with increased compressor RPMs and source side EWT. Also, using the counter flow method, compared to the parallel flow method, improves the COP by approximately 5.9% for an ISO 13256-2 rated condition.

80%에서 120%로 증 가할 때 흡수액 농도가 56%, 55%, 54%, 53%에서의 열교환량은 각각 30%, 33%, 34%, 37% 정도 증가하 였다 또한 고온재생기의 흡수액 입구농도가 . 56%, 55%, 54%, 53% 일 때 공기측 입구온도가 170 o C에서 210 o C로 증가함에 따라 고온재생기의 열교환량은 각각 140%, 160%, 220%, 224% 정도 증가하였다 . Abstract: An absorption chiller-heater using only a natural refrigerant hardly causes any environmental pollution. In an absorption chiller-heater, the performance of its high-temperature generator, which uses exhaust gases, is essential to achieving superior system performance. To investigate the performance of such a high-temperature generator, a laboratory-scale high-temperature generator working with exhaust gases was designed and tested. Changes in the performance of the high-temperature generator as a function of inlet conditions of the absorbing solution, such as air inlet temperature and mass flow, were investigated. It was observed that when the air mass flow rate ratio was increased from 80% to 120%, the heat capacity was increased by 30%, 33%, 34%, and 37%, respectively. Additionally, when the air inlet temperature was elevated from 170°C to 210°C for absorption solution concentrations of 56%, 55%, 545, and 53%, the heat capacity increased by 140%, 160%, 220%, and 224%, respectively.

The analysis of performance characteristics was carried out in the plate type evaporator with counter and parallel flow. To investigate performance of evaporator with water inlet temperature and refrigerant mass flow rate were changed. As a result, when the inlet temperature of water is 8 o C, capacity of parallel flow evaporator higher than counter flow is 0.35%. But as the inlet temperature of water rises from 8 o C to 16 o C, capacity of counter flow type evaporator higher than parallel flow type is 0.12%, 0.27%, 1.1%, 1.6%, respectively. The findings showed that counter flow type evaporator has a larger capacity than those that were parallel flow type evaporator. As the refrigerant mass flow rate rises, capacity and pressure drop increases in the counter and parallel flow type evaporator. Key Words ：Counter flow, Parallel flow, Evaporator, Plate heat exchanger, R410a *†권오경(교신저자) : 한국생산기술연구원E-mail : kwonok@kitech.re.kr, Tel : 041-589-8528 *배경진 : 한국생산기술연구원*차동안 : 한국생산기술연구원*†Oh-Kyung Kwon(corresponding author) : Energy System R&D Group, Korea Institute of Industrial Technology.E-mail : kwonok@kitech.re.kr, Tel : 041-589-8528 *Kyung-Jin Bae : Energy System R&D Group, Korea Instituteof Industrial Technology.*Dong-An Cha : Energy System R&D Group, Korea Institute of Industrial Technology.

The performance of a plate heat exchanger for using liquid solution in the absorp- tion chiller-heater was analyzed. The model was developed by using the various performance prediction correlations. The performance characteristics of the plate heat exchanger with the mass flow rate ratio was verified by using experimental data. To investigate performance of plate heat exchanger with geometry variables, the chevron angle, corrugated wave length, and corrugation depth were changed. As a result, the capacity of Kim and Martin correlation models was similar with the experimental data, and the capacity difference was less than 2%. Besides, the pressure drop of Marin correlation model showed a similar variation with experimental data, and the difference of pressure drop was less than 1.5 kPa.

The poet-lover in Astrophil and Stella is generally considered to be conflicting between reason and passion pining for an unattainable beloved lady. The plot and the themes of the sequence are highly conventional, derived from Petrarch and his many Italian, French and Spanish imitators. However, the poet-lover also claims that he protests this Petrarchan convention in his search of fresh and original ways of writing. Thus the sequence has been studied as a counter-discourse of English Petrarchism and has been given more focus on its writing skills. On the other hand, this paper aims to examine the poet-lover not as an anti-Petrarchan lover but as an anti-courtly lover in a way to reveal some unfamiliar and unexpected aspects of a star-crossed lover. This paper examines that the poet-lover is rebellious in accepting the decrees of love, proud in his estimation and presentation of his own values, cruel and dishonorable in vengeance on his ungrateful lady, and presumptuous and impudent in admitting his desire. These uglier and more disappointing characteristics are quite opposite of those the readers generally expect from a lover in the standard of courtly love. While the poet-lover dramatically transforms the standard of courtly love in order to write most persuasively and most attractively, Sidney reveals that the villain images of the poet-lover as an anti-courtly lover is nothing but guises and masks he conveniently adopts and discards in order to carry out experiments in the dramatization of self. The study intended to examine some unfamiliar aspects of the protagonist leads to the conclusion that Sidney manages to infuse his sonnets with an extraordinary vigor and freshness by appropriating the convention and the concepts of courtly love.

The increase of mobile devices is addressing a mobility support to facilitate handovers of mobile devices. Mobile IPv6 (MIPv6) has been proposed by IETF to solve this problem in the Internet. But, in MIPv6, there is a time interval that a mobile node (MN) cannot send or receive any packets during the handovers. The time interval is long enough for packets to be lost so that it is intolerable to be used for real-time traffics. Therefore, it is necessary to find out the method to reduce a handover latency. For this reason, Fast Handovers for Mobile IPv6 (FMIPv6) protocol has been proposed to reduce the MIPv6 handover latency. In FMIPv6, there are two operation modes due to the unpredictability of MN's mobility; the predictive mode and the reactive mode. In this paper, we discuss two modes of FMIPv6 and compare their performance with MIPv6 in a real test-bed network. The performance result shows that FMIPv6 has better handover performance than MIPv6 does. But, it also shows that FMIPv6 still suffers from the handover disruption time due to the IEEE 802.11 MAC layer handover. I. INTRODUCTION

In wireless ad hoc networks, many multicast routing protocols are proposed such as ODMRP, MAODV, etc. In general, the IEEE 802.11 standard is assumed as a MAC protocol in those protocol and multicast data packets are transmitted at the basic transmission rate which is 2Mbps at the IEEE 802.11 or 802.11b. However, if the multicast packet can be transmitted at higher transmission rates than 2Mbps in a multi-rate WLAN such as IEEE 802.11b, we can achieve higher throughput gain and lower transmission delay than those at 2Mbps transmission rate. In this paper, we propose a new multicast routing protocol in multi-rate wireless ad hoc networks. In the proposed protocol, we design a multicast mesh creation method considering multiple transmission rates between any two nodes in the ad hoc networks. We also design a multicast mesh maintenance scheme when the transmission rate between two nodes comprising a multicast mesh is changed because of node mobility. The performance of the proposed protocol is compared with ODMRP using ns2 simulation, and the proposed protocol shows higher packet delivery ratio and lower end-to-end delay than the ODMRP.

Mobile IPv6, which is a protocol being standardized by IETF for global IP mobility support, is expected to play a key role for future all-IP wireless networks. As the demands for delay sensitive real-time applications increase, the handover latency of mobile IPv6 becomes inadequate for these applications. There have been many proposals, such as fast handovers for mobile IPv6 (FMIPv6), to tackle this problem. However, FMIPv6 only concentrates on the protocol operation while it does not address other issues, such as radio access discovery and candidate access router discovery, that are critical to the handover performance of FMIPv6. Therefore, in this paper, we propose ARIP (access router information protocol), which performs a candidate access router discovery and a radio access network discovery in one protocol suite, to provide an efficient handover framework for MIPv6 and FMIPv6. ARIP is designed to cope with heterogeneous networks as well as homogeneous networks and to be closely coupled with FMIPv6 to provide an efficient handover operation. The performance evaluation of MIPv6, FMIPv6, and FMIPv6 with ARIP is performed in an actual network environment and the performance results show that FMIPv6 with ARIP gives the best performance in terms of handover latency