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首页> 外文学位 >Determining the quality and quantity of heat produced by proton exchange membrane fuel cells with application to air-cooled stacks for combined heat and power.
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Determining the quality and quantity of heat produced by proton exchange membrane fuel cells with application to air-cooled stacks for combined heat and power.

机译：确定质子交换膜燃料电池产生的热量的质量和数量，并将其应用于风冷电池组以结合热量和功率。

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摘要

This thesis presents experimental and simulated data gathered specifically to assess air-cooled proton exchange membrane (PEM) fuel cells as a heat and electrical power source for residential combined heat and power (CHP). The experiments and simulations focused on the air-cooled Ballard Nexa fuel cell. The experimental characterization provided data to assess the CHP potential of the Nexa and validate the model used for the simulations. The model was designed to be applicable to any air-cooled PEM fuel cell.;To improve performance as a CHP heat engine, the Nexa and other air-cooled PEM fuel cells need to expel coolant at temperatures above 325 K. To determine if PEM fuel cells are capable of achieving this coolant temperature, a model was developed that simulates cooling system heat transfer. The model is specifically designed to determine coolant and stack temperature based on cooling system and stack design (i.e. geometry). Simulations using the model suggest that coolant mass flow through the Nexa can be reduced so that the desired coolant temperatures can be achieved without the Nexa stack exceeding 345 K during normal operation.;Several observations are made from the presented research: 1) PEM fuel cell coolant air can be maintained at 325 K for residential space heating while maintaining the stack at a temperature below the 353 K Nafion design limits chosen for the simulations; 2) The pressure drop through PEM cooling systems needs to be considered for all stack and cooling system design geometries because blower power to overcome the pressure drop can become very large for designs specifically chosen to minimize stack temperature or for stacks with long cooling channels; 3) For the air-cooled Nexa fuel cell stack, heat transfer occurring within the fuel cell cooling channels is better approximated using a constant heat flux mean Nusselt correlation than a constant channel temperature Nusselt correlation. This is particularly true at higher output currents where stack temperature differences can exceed 8 K.;Based on hourly load data, four Nexa fuel cells would be required to meet the peak electrical load of a typical coastal British Columbia residence. For a year of operation with the four fuel cells meeting 100% of the electrical load, simultaneous heat generation would meet approximately 96% of the space heating requirements and overall fuel cell efficiency would be 70%. However, the temperature of the coolant expelled from the Nexa varies with load and is typically too low to provide for occupant comfort based on typical ventilation system requirements. For a year of operation, the coolant mean temperature rise is only 8.3 +/- 3.4 K above ambient temperature.
机译：本文提出了专门收集的空气动力学质子交换膜（PEM）燃料电池作为住宅热电联产（CHP）的热电电源的实验和模拟数据。实验和模拟的重点是风冷巴拉德Nexa燃料电池。实验表征为评估Nexa的CHP潜力和验证用于仿真的模型提供了数据。该模型设计为适用于任何风冷PEM燃料电池。；为提高作为热电联产热力发动机的性能，Nexa和其他风冷PEM燃料电池需要在325 K以上的温度下排出冷却液。燃料电池能够达到该冷却液温度，因此开发了一个模型来模拟冷却系统的热传递。该模型经过专门设计，可根据冷却系统和烟囱设计（即几何形状）确定冷却液和烟囱温度。使用该模型进行的仿真表明，可以降低通过Nexa的冷却剂质量流量，从而在正常运行期间Nexa烟囱温度不超过345 K的情况下可以实现所需的冷却剂温度。；从本研究中获得的一些观察结果是：1）PEM燃料电池可以将冷却空气保持在325 K以用于居住空间供暖，同时将烟囱的温度保持在为模拟选择的353 K Nafion设计极限以下； 2）对于所有烟囱和冷却系统设计几何形状，都必须考虑通过PEM冷却系统的压降，因为对于专门选择用于降低烟囱温度的设计或具有较长冷却通道的烟囱，克服压降的鼓风机功率可能会变得非常大； 3）对于风冷的Nexa燃料电池堆，与恒定的通道温度Nusselt相关性相比，使用恒定的热通量平均Nusselt相关性更好地估计了在燃料电池冷却通道内发生的热传递。在烟囱温度差可能超过8 K的较高输出电流下尤其如此；基于每小时的负载数据，将需要四个Nexa燃料电池来满足典型的不列颠哥伦比亚省沿海住宅的峰值电负载。在四个燃料电池满足100％的电负载的情况下运行一年，同时产生的热量将满足大约96％的空间供暖要求，而总体燃料电池效率将达到70％。但是，从Nexa排出的冷却剂的温度会随负载而变化，并且通常过低，无法根据典型的通风系统要求为乘员提供舒适感。在运行一年中，冷却液的平均温度仅比环境温度高8.3 +/- 3.4K。

著录项

  • 作者

    Schmeister, Thomas.;

  • 作者单位

    University of Victoria (Canada).;

  • 授予单位 University of Victoria (Canada).;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 147 p.
  • 总页数 147
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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