Effects of Anode Flow Field Design on CO2 Bubble Behavior in μDMFC

Clogging of anode flow channels by CO2 bubbles is a vital problem for further performance improvements of the micro direct methanol fuel cell (μDMFC). In this paper, a new type anode structure using the concept of the non-equipotent serpentine flow field (NESFF) to solve this problem was designed, fabricated and tested. Experiments comparing the μDMFC with and without this type of anode flow field were implemented using a home-made test loop. Results show that the mean-value, amplitude and frequency of the inlet-to-outlet pressure drops in the NESFF is far lower than that in the traditional flow fields at high μDMFC output current. Furthermore, the sequential images of the CO2 bubbles as well as the μDMFC performance with different anode flow field pattern were also investigated, and the conclusions are in accordance with those derived from the pressure drop experiments. Results of this study indicate that the non-equipotent design of the μDMFC anode flow field can effectively mitigate the CO2 clogging in the flow channels, and hence lead to a significant promotion of the μDMFC performance

An experimental and numerical investigation of the use of liquid flow in serpentine microchannels for microelectronics cooling

This paper presents a combined experimental and numerical investigation of single-phase water flow and heat transfer in serpentine rectangular microchannels embedded in a heated copper block. The performance of four different microchannel heat sink (MCHS) configurations are investigated experimentally, the first having an array of straight rectangular microchannels (SRMs), while the other have single (SPSMs), double (DPSMs) and triple path multi-serpentine rectangular microchannels (TPSMs). Three-dimensional conjugate heat transfer models are developed for both laminar and turbulent single-phase water flows in each of these MCHSs and the governing flow and energy equations solved numerically using finite elements. The numerical predictions of pressure drop (∆P) and average Nusselt number (〖Nu〗_avg) are in good agreement with experimental data, and indicated that the single path serpentine microchannel (SPSM) leads to a 35% enhancement of the 〖Nu〗_avg at a volumetric flow rate of 0.5 l/min and a 19% reduction in total thermal resistance (R_th) compared to the conventional SRM heat sink. However, this enhancement is at the expense of a large (up to ten-fold) increase in ∆P compared to the SRM heat sink, so that a suitable compromise must be struck between heat transfer and pressure drop in practical MCHS designs

Mycosis Fungoides: The great imitator

Introduction: Mycosis fungoides although a cutaneous T-Cell lymphoma can immitate many dermatological disorders. A 60 year old man presented to our hospital with generalized annular plaques, few with verrucous surface. The annular lesions imitated Psoriasis, Tinea, Syphilis and the diagnosis was in dilemma. Histopathology gave the light and path to diagnosis. Case report: A 60 year old man presented with complains of erythematous scaly lesions since 20 year, Lesions were initially flat and erythematous which later became ulcerated, crusted and painful. H/O exacerbation and remission was present. Conclusions: Mycosis Fungoides is a great imitator both clinically and histopathologically. We are presenting a case report of patient with Mycosis Fungoides, Stage IIA

Livedo reticularis: A review of the literature

Livedo reticularis (LR) is a cutaneous physical sign characterized by transient or persistent, blotchy, reddish-blue to purple, net-like cyanotic pattern. LR is a benign disorder affecting mainly middle-aged females, whereas livedo racemosa (LRC) is pathologic, commonly associated with antiphospholipid antibody syndrome. This article aims to review the causes of LR and LRC along with the evaluation and management