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Energy conservation and emission reduction are critical global concerns, with infrared gas stoves recognized for their superior thermal efficiency and low emissions. However, research on infrared gas stoves with vertical ejectors, particularly those designed for use in horizontally constrained spaces, remains sparse. To bridge this gap, an experimental system is constructed to investigate the effects of perforated plate height, nozzle exit position (NXP), and heating height on stove performance. The experimental results reveal that gas uniformity is significantly influenced by the height of the perforated plate, while NXP has a lesser impact. The optimal height of the perforated plate is 12 mm, and the recommended value for NXP is −4 mm. With the heating height increasing from 15.0 mm to 36.5 mm, the thermal efficiency of the infrared gas stove decreases from 70.2 % to 59.3 %. The concentration of carbon monoxide in the flue gas initially declines sharply then gradually increases with the increase of heating height. Meanwhile, the concentration of nitrogen oxide exhibits slight fluctuations, with a mere 2 ppm difference between maximum and minimum values. Based on the results, a heating height of 19.3 mm is recommended. This study provides guidance for optimizing domestic gas stoves.

Utilization of gas engine-driven heat pumps (GEHP) can reduce the heavy loads on the power grid when electric heat pumps operate during the heating season. This study is to examine the performance of GEHP as a water heater with different engine speeds and water flow rates providing space-heating and sanitary hot water. When the engine speed rises from 1400 rpm to 1900 rpm, the temperature rise of water increases by 37% from 25.7 °C to 35.3 °C. Moreover, the system heat capacity rises from 71.8 kW to 97.7 kW with an increase of 36%, while the COP decreases from 3.6 to 3.0. As the inlet water flow rate an increase from 2.5 m3/h to 4.0 m3/h, the temperature rise decreases from 44.3 °C to 24.1 °C, with decreasing heat capacity from 128.8 kW to 112.1 kW. Additionally, the primary energy ratio (PER) initially increases from 1.46 to 1.50 at the engine speed of 1800 rpm, followed by a slight decrease to 1.48 when the engine speed reaches 1900 rpm. With an increasing water flow rate, the PER achieves its highest value of 1.64 at 3 m3/h and its lowest value of 1.49 at 3.5 m3/h.

Regenerative combustion technology has many advantages such as fuel saving, high combustion efficiency and low emission, and it has been widely used for large-scale furnaces. However, when regenerative combustion technology is adopted for small-scale furnaces, many technical problems occur. In this paper, a small-scale regenerative furnace with heat load of 70–80 kW and primary air coefficient of 1.00–1.60 was designed. It was found that the flame shifts from bright pale blue with faint rotating streamlines to yellowish transparent without apparent streamlines and to bright and transparent eventually. When main burners work stably, the temperature inside the furnace raises rapidly at first, and then the temperature increases steadily and fluctuates periodically. The highest temperature in the furnace can reach around 1300 °C. As the reversing time increases, the temperature fluctuation becomes more dramatically and the highest temperature is higher. NOx concentrations at all measurement points are below 50 ppm. Heat transfer efficiencies of each heat retainer show an increasing trend with the rise of the number of reversions. As reversing time increases, the heat transfer efficiency shows a decreasing trend.

With the increasingly stringent requirements for nitrogen oxide emissions, fully premixed water-cooled burners have been gradually discussed and studied due to their low cost and obvious effect on NOx reduction. However, their application in civil gas appliances is relatively rare, and there are few systematic studies combining experiments and simulations. In this paper, the experimental research and numerical simulation of the water-cooled burner are firstly carried out, and the accuracy of the numerical model is verified by the measured results. Then, the location and influencing factors of NOx generation are analyzed, and the direct factors affecting NOx generation in the water-cooled combustion technology are determined. The results show that the primary air coefficient is the main factor affecting the formation of NOx, the secondary air has little effect on the formation of NOx, and the premixed air temperature has little effect on it. The results have certain guiding significance for the design of water-cooled burners.

The application of gas engine driven heat pump (GHP) system can improve the peak valley difference of power and gas system and promote the low-carbon utilization of energy system. The energy consumption of GHP system in different types of buildings and especially the coefficient of performance (COP) under partial load rate needs more analysis. In this paper, according to the local meteorological parameters in Shanghai, the COP operation curve of GHP and electric driven heat pump (EHP) units under partial load rate was analyzed. Combined with the load calculation, the annual energy consumption of GHP and EHP units in different types of buildings, and the influence of energy price on economy of GHP system were analyzed. For office buildings and catering buildings, the energy consumption and operating costs of GHP system were slightly lower than those of EHP system, while for hotel buildings, the annual operating costs of GHP were lower than those of EHP only when the winter gas price was 2.39 yuan/m3 and the summer gas price was 2.19 yuan/m3. Therefore, in order to promote the market competitiveness of gas air conditioning, it is necessary to further refine the gas price or charge standard.

To study the effect of hydrogen-blended natural gas on the combustion stability and emission of domestic gas water heater, a test system is built in this paper, taking a unit of the partial premixed burner commonly used in water heaters as the object. Under the heat load of 0.7–2.3 kW, the changes of flame shape, burner temperature and pollutant emission of natural gas with hydrogen volume ratio of 0–40% are studied with independent control of primary air supply and mixing. The results show that: with the increase of hydrogen blending ratio, the inner flame height increases firstly and then reduces, while the change of burner temperature is opposite. The maximum inner flame height and the minimum temperature of the burner both appear at the hydrogen blending ratio of 10–20%. It can be seen that the limit of hydrogen blending ratio which can maintain the burner operate safely and stably under rated heat load is 40% through the maximum temperature distribution on the burner surface. The CO emission in the flue gas gradually decreases with the increase of hydrogen blending ratio, while the NOx emission fluctuates slightly when the hydrogen blending ratio is less than 20%, but then decreases gradually.

De-carbonization actions, represented by the electrification of end-use energy sources, have been strongly promoted, while space heating in residential buildings is an important aspect. In this paper, Jinan and Qingdao in northern China are selected to explore the challenges that electrification of heating will bring. The electricity demand for heating of different types of buildings is simulated, with the assumption that all heating loads are provided by electric heat pumps. Then the comparison of heating electricity demand with current electricity consumption in various social sectors has been analyzed to investigate the impact of the newly added electrical load on the power grid. The annual dynamic power supply under the currently installed wind turbines and photovoltaic modules is calculated to explore the interrelationship between the power supply potential of the available renewable energy and the heating electricity demand. The results show that the implementation of heating electrification will bring a strong impact on the existing grid, with photovoltaic generation almost negligible during the heating period and wind generation severely affected by intermittency. In the future, the deployment of installed renewable energy needs to continue to be promoted, while the layout of energy storage facilities needs to be strengthened.

As the second-largest contributor to historical global warming, methane emissions must be controlled to slow down temperature increase and achieve climate benefits. Due to a lack of knowledge about the specific sources and processes, a quantitative approach will lead to inaccurate estimation. In this paper, a typical local distribution company with more than 100 years of operation history was chosen. Detailed procedures of pipeline constructions and accidents were investigated, and critical steps leading to methane emissions were clarified. Then emission quantification methodologies for all processes were proposed, including a new pipeline connection, new regulator connection, emergency repair and third-party damages. As a basis for emission estimation, the distribution of parameters, such as diameter, length and pressure, was counted. Then the emission rates of all projects were calculated, and emission factors were established. The average emission rates of the new pipeline connection, new regulator connection, emergency repair, third-party damage (medium pressure) and third-party damage (low pressure) were 234 kg, 147 kg, 217 kg, 17,282 kg and 62 kg, respectively. In addition, the total methane emission in China from these sources was estimated to be about 5 × 104 t, which is large enough to attract attention. The work in this paper aims to establish a reasonable framework to evaluate venting methane emissions from the distribution process of natural gas.