Empirical Study on The Heat Exchange Effectiveness of A Cross-flow Thermoelectric Air To Air Heat Pump Unit

A thermoelectric module (TEM), non-vapor compression heat pump, has attracted research interesting as a substitution of the conventional vapor compression heat pump. However, there are few studies for analysing a heat exchange effectiveness and performance of TEM for application to the HVAC system. The purpose of this research is to propose an empirical model for predicting the heat exchange effectiveness in air heat-pump system using TEM. The proposed system consists of aflat plate fin array that is heat exchanger integrated TEM for cooling and heating. In this study, the enthalpy efficiency is adopted as the TEM heat exchange performance index. And then, the inlet and outlet air temperature and humidity ratio, air flow rate at the heating and cooling side, TEM surface temperature, heat exchange area, and input direct current (DC) to the TEM are measured to calculate the enthalpy efficiency. The data were statistically analysed by the response surface methodology (RSM) and analysis of variance (ANOVA). Using the response surface methodology (RSM) and analysis of variance (ANOVA), the experimental data were statistically analyzed. Design parameters had significant impact on the heat exchange effectiveness of the flat plate heat exchanger integrated TEM for air cooling and heating. Consequently, two polynomial equations that predict heat exchange effectiveness at the cold and hot sides of the TEM heat pump were derived as a function of the selected design parameters and were used to calculate the outlet air temperature at cooling and heating side

Investigation Of Desirable Arrangement Of Thermoelectric Modules For The Radiant Cooling Panel

The thermoelectric module radiant cooling panel (TEM-RCP) is an alternative of the conventional hydraulic radiant cooling panels which has advantages of no refrigerant, no chemical reactions, and no moving parts. In addition, it has merits of easy control, fast response through direct heat absorption from TEM without water. However, there are few guidelines for designing the TEM-RCP and no study suggested how to arrange the thermoelectric modules for the radiant cooling panel. Therefore, this study aims to propose the desirable arrangement of thermoelectric modules for radiant cooling panel. To achieve this purpose, the design methods for TEM-RCP was developed based on the semi-black box model of TEM and 2D finite difference method. The mock up model of TEM-RCP was constructed to validate the proposed model and results. The TEM-RCP we constructed is composed of 7 TEMs, the aluminium plate, the heat sink attaching on the TEMs, duct and fan. The panel temperature is maintained in 16 at the cold side of TEM and rejected heat from hot side of TEM is removed by using fan. The design point we focused was the distribution of panel temperature according to the ASHRAE Handbook. Therefore, we investigated optimal array and distance between TEMs not to excess the maximum temperature difference 3 across a given grid. As a result, it is revealed that the triangular grid is the best grid for even temperature distribution of TEM-RCP and the optimal distance between TEMs is 0.2 m to 0.3 m according to the room condition and operation characteristics of TEM. The optimized results is verified using the mock up model of TEM-RCP in the laboratory experiments

Experimental Verification of Indirect Evaporative Cooling-Assisted Internally Cooled Liquid Desiccant Dehumidifier

The main objective of this paper is to estimate the system performance of an evaporative cooling assisted outdoor air system for air conditioning a data center. To evaluate the computer room air conditioning (CRAC) system used evaporative cooling technology, a mock-up for evaporative cooling assisted outdoor air system was designed. The feasibility of the evaporative cooling assisted outdoor air system is analysed by experimental test for a modular data center in Anseong, Korea. A mock-up system is designed by 43,000 m3/h of design fan flow, 160kW of the cooling capacity for air conditioning a data center. A design condition for the indirect evaporative cooler was set in 50% of sensible heat exchange efficiency and 65% of indirect evaporative cooling efficiency, respectively. A server rack simulator was installed to adjust the 160kW of sensible heat emission of modular data center. The experiment results show that the 59% of a sensible heat exchange efficiency and 78% of indirect evaporative cooling efficiency under experimental conditions

Removal Effect of Bio-contaminants in a Packaged Liquid Desiccant-assisted Air Conditioning Unit

The purpose of the study is to evaluate the removal effects of microbial contamination, such as fungi and bacteria, on a packaged liquid desiccant-assisted air conditioning unit. Recently, a package unit of a liquid desiccant and indirect and direct evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS) was proposed. The LD-IDECOAS consists of a liquid desiccant system, an indirect evaporative cooler, and a direct evaporative cooler. The test was conducted under operating conditions during the cooling season when the LD-IDECOAS operates a liquid desiccant system, an indirect evaporative cooler, and a direct evaporative cooler. The sampling is performed at the inlet (outdoor air) and outlet (supply air) of the package unit. Fungi were cultured in a potato dextrose agar (PDA) medium, and bacteria were cultured in a tryptic soy agar (TSA) medium as indices of bio-contaminants. The results indicated that the concentration of fungal contamination in the supply air (that passes through the package unit) decreased by 7.7% when compared to that of outdoor air. The concentration of bacterial contamination in the outlet was also reduced by 72.4% when compared to that in the inlet. Hence, the package unit improves air quality by removing bio-contaminants, such as fungi and bacteria, although unexpected contamination occurred in the experiment

Energy Efficiency of Seasonal Solar Thermal Energy Storage System for Greenhouse Heating

Seasonal Thermal Energy Storage (STES) is widely researched for having benefits in that it utilizes excess energy which would be wasted otherwise. The purpose of this study is to analyze energy efficiency of seasonal solar thermal energy system as heating system for greenhouses and compare it with conventional variable air volume (VAV) heating system. Greenhouse was chosen as a simulation model because it requires constant and stable heating through winter season to extend growing season and also because greenhouse can provide enough area to install solar collectors and heat storage tanks. The proposed seasonal solar thermal energy storage system consists of solar thermal collector, fully mixed heat storage tank, and VAV system. Energy simulation was conducted in two steps: heat storing in summer season, and heating in winter season. For greenhouses with area sizing 1600 m2, solar thermal collector of 1250 m2 and heat storage tank of 2000 m3 were designed. TRNSYS 17 and engineering equation solver (EES) were implemented for simulation and calculation of the systems thermal data. Simulation results showed the tank water temperature rising up to optimal temperature (95 oC) before heating season, and STES heating contributed to 55% of total heating load. Consequently, 30% of total heating cost was cut down showing energy efficiency of seasonal solar thermal energy storage system

Comparison of Dehumidification Performance of Counter and Cross-flow type Liquid desiccant Dehumidifiers

In HVAC systems, a liquid desiccant system has attracted research attentions due to its advantages on removing latent loads in a conditioned building with less energy consumption. The dehumidifier is the key component in a liquid desiccant system, whose heat and mass transfer performance directly affects the whole dehumidification performance. The coupled heat and mass transfer performance is affected not only by the properties of packing material and inlet conditions of air and desiccant solution, but also by the flow direction between air and desiccant solution. This paper experimentally investigates the dehumidification performance of the counter-flow type and cross-flow type liquid desiccant system under the same system operation conditions. In this study, Lithium chloride aqueous solution is used as a desiccant solution and Celdek structure packing is used. The enthalpy efficiency and moisture efficiency were adopted as the dehumidification performance indices. To investigate the impact of air and solution conditions on the two indices, five parameters were measured: liquid to gas ratio, the inlet air temperature and humidity ratio and solution temperature and concentration. As a result, the effects of flow directions between air and solution on the dehumidification process in various conditions were analysed. In additions, the correlations for predicting the performance of the two type of liquid desiccant system are proposed, which are good agreement with the experiment results and existing models

Surgical management of pilon fractures with large segmental bone defects using fibular strut allografts: a report of two cases

We present two patients with open pilon fractures with large bone defects treated successfully with fibular strut allografts. The patients were initially treated by massive irrigation, wound debridement, and temporary external fixation. After complete wound healing, the bone defects were managed. Because autologous iliac crest or fibular bone grafts were impossible to be harvested due to multiple fractures, the bone defects were reconstructed with fibular strut allografts. Fixation was performed with a periarticular distal tibia locking plate. At 2 months postoperatively, the patients ambulated with partial weight-bearing; at 6 months, they had full range of motion of the ankle joint and full weight-bearing

LYL1 gene amplification predicts poor survival of patients with uterine corpus endometrial carcinoma: analysis of the Cancer genome atlas data

Background Somatic amplifications of the LYL1 gene are relatively common occurrences in patients who develop uterine corpus endometrial carcinoma (UCEC) as opposed to other cancers. This study was undertaken to determine whether such genetic alterations affect survival outcomes of UCEC. Methods In 370 patients with UCEC, we analysed clinicopathologic characteristics and corresponding genomic data from The Cancer Genome Atlas database. Patients were stratified according to LYL1 gene status, grouped as amplification or non-amplification. Heightened levels of cancer-related genes expressed in concert with LYL1 amplification were similarly investigated through differentially expressed gene and gene set enrichment analyses. Factors associated with survival outcomes were also identified. Results Somatic LYL1 gene amplification was observed in 22 patients (5.9%) with UCEC. Patients displaying amplification (vs. non-amplification) were significantly older at the time of diagnosis and more often were marked by non-endometrioid, high-grade, or advanced disease. In survival analysis, the amplification subset showed poorer progression-free survival (PFS) and overall survival (OS) rates (3-year PFS: 34.4% vs. 79.9%, P = 0.031; 5-year OS: 25.1% vs. 84.9%, P = 0.014). However, multivariate analyses adjusted for tumor histologic type, grade, and stage did not confirm LYL1 gene amplification as an independent prognostic factor for either PFS or OS. Nevertheless, MAPK, WNT, and cell cycle pathways were significantly enriched by LYL1 gene amplification (P < 0.001, P = 0.002, and P = 0.004, respectively). Conclusions Despite not being identified as an independent prognostic factor in UCEC, LYL1 gene amplification is associated with other poor prognostic factors and correlated with upregulation of cancer-related pathways

Identifying a low-risk group for parametrial involvement in microscopic Stage IB1 cervical cancer using criteria from ongoing studies and a new MRI criterion

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.Abstract Background There are currently three ongoing studies on less radical surgery in cervical cancer: ConCerv, GOG-278, and SHAPE. The aim of this study was to evaluate the performance of the criteria used in ongoing studies retrospectively and suggest a new, simplified criterion in microscopic Stage IB1 cervical cancer. Methods A retrospective analysis was performed in 125 Stage IB1 cervical cancer patients who had no clinically visible lesions and were allotted based on microscopic findings after conization. All patients had magnetic resonance imaging (MRI) after conization and underwent type C2 radical hysterectomy. We suggested an MRI criterion for less radical surgery candidates as patients who had no demonstrable lesions on MRI. The rates of parametrial involvement (PMI) were estimated for patients that satisfied the inclusion criteria for ongoing studies and the MRI criterion. Results The rate of pathologic PMI was 5.6% (7/125) in the study population. ConCerv and GOG-278 identified 11 (8.8%) and 14 (11.2%) patients, respectively, as less radical surgery candidates, and there were no false negative cases. SHAPE and MRI criteria identified 78 (62.4%) and 74 (59.2%) patients, respectively, as less radical surgery candidates; 67 patients were identified as less radical surgery candidates by both sets of criteria. Of these 67 patients, only one had pathologic PMI with tumor emboli. Conclusions This study suggests that the criteria used in three ongoing studies and a new, simplified criterion using MRI can identify candidates for less radical surgery with acceptable false negativity in microscopic Stage IB1 disease