Heat is the most essential form of energy for mankind lives. Steam is the most widely used as heat-carrying medium in the world. The boiler is the best system for the conversion of chemical energy contained in fuels into steam or hot fluid. According to the efficiency of all existing boilers, one of the most important factors that substantially affect this boiler performance index is the stack losses. This research proposed a novel direct-fired porous boiler (DPB). Because of it has no stack losses, this proposed boiler could outperforms all of the existing boilers. The purpose of this article is to discuss the potential of enhancing the suggested DPB performance by using different physical characteristics of packed-bed porous medium (PPM). The experimental results show that among the four most bed shapes available in the market and have a high heat transfer aspect, the hex-nut shape has been selected to use in the proposed DPB. At the heat input rate of about 14 kW, the steam generation rate of about 20 kg/h, (at 1.5 barg and 300 °C), is obtained. Because it has only surface heat loss, thermal efficiency of more than 98% can be achieved. It can be concluded that the possibility of using a hex-nut bed as a packed bed porous medium in a low-pressure porous boiler is confirmed with the proposed boiler.

热量是人类生活中最基本的能量形式。蒸汽是世界上使用最广泛的载热介质。锅炉是将燃料中含有的化学能转化为蒸汽或热流体的最佳系统。根据所有现有锅炉的效率，对锅炉性能指标产生重大影响的最重要因素之一是烟囱损失。本研究提出了一种新型直燃多孔锅炉（DPB）。由于它没有烟囱损失，这个提议的锅炉可以胜过所有现有的锅炉。本文的目的是讨论通过使用填充床多孔介质 (PPM) 的不同物理特性来提高建议的 DPB 性能的潜力。实验结果表明，在市场上最常见的四种床形中，具有高传热性，六角螺母形状已被选择用于提议的 DPB。在约 14 kW 的热输入速率下，获得约 20 kg/h 的蒸汽生成速率（在 1.5 barg 和 300 °C 下）。由于只有表面热损失，热效率可达98%以上。可以得出结论，所提出的锅炉证实了在低压多孔锅炉中使用六角螺母床作为填充床多孔介质的可能性。热效率可达98%以上。可以得出结论，所提出的锅炉证实了在低压多孔锅炉中使用六角螺母床作为填充床多孔介质的可能性。热效率可达98%以上。可以得出结论，所提出的锅炉证实了在低压多孔锅炉中使用六角螺母床作为填充床多孔介质的可能性。