耦合热泵换热器的原理及变工况性能研究

工业能耗占我国总能耗超过70%,而其能源利用效率不足50%,因此工业余热高效回收利用是节能减排的重要途径之一。热泵技术是提升能量品位的有效方法,但吸收式热泵需要配置三个不同温度品位的热源或热汇,而电动热泵受热力学循环、工质物性、压缩机耐温耐压限制以及避免润滑失效一般只能工作于有限温度范围(<100℃)之内,因此该研究将吸收式循环与压缩式循环进行深度耦合,用于直接回收工业余热制取高温热水,同时确保压缩机的安全稳定运行.该文首先分析耦合热泵换热器的运行原理,其次建立了耦合热泵换热器的数学模型,最后对模型进行求解分析了关键参数对耦合热泵换热器性能影响变化规律。在设计工况下,当制取133℃热水时,耦合热泵换热器COP达到3.6,压缩机排气压力为1.2 MPa,排气温度为79℃,远低于压缩机耐温耐压上限和润滑油失效温度,因此耦合热泵换热器在利用余热制取高温热水或蒸汽领域具有一定的应用潜力。     

冷源方式选择对CEC影响的分析

以空调系统能耗系数CEC(Coefficient of Energy Consumption)即空调设备全年总能量消耗量与假想空调负荷累计值之比作为空调系统能耗性能评价指标,对天津地区某典型办公大楼建筑空调系统选用水源热泵和溴化锂冷热水机组条件下的能耗状况进行计算与分析。并证明了与采用水源热泵的空调系统相比较,采用溴化锂冷水机组的空调系统节电不节能。     

1.57 MW peak power pulses generated by a diode-pumped Q-switched Nd:LuAG ceramic laser

The pulse characteristics of a laser diode dual-end-pumped electro-optic Q-switched Nd:LuAG ceramic laser at various repetition rates are presented. The largest output pulse energy of 11 mJ is realized at the repetition rate of 100 Hz with pump energy of 84.3 mJ, and the slope efficiency in respect to pump pulse energy is 18.6%. The single pulse peak power reaches up to 1.57 MW. Using Nd:LuAG ceramic as the amplification medium seeded by an Nd:YAG laser of 5.2 mJ, a 10.3 mJ amplified pulse is obtained with pump pulse energy of 42.8 mJ, corresponding to an extraction efficiency of 11.9%.     

Intracavity optical parametric oscillator at 1572-nm wavelength pumped by passively Q-switched diode-pumped Nd:YAG laser

An intracavity optical parametric oscillator (IOPO) based on bulk KTP crystal was constructed with a Nd:YAG slab as an active medium pumped by a 300-W diode array and Cr:YAG as a passive Q-switch. A signal pulse of 1.9-mJ energy at 1572-nm wavelength was demonstrated. In the cavity, optimized with respect to single-pulse energy, a five-fold shortening of signal-pulse duration with respect to 1064-nm pump radiation was observed. A twice as large level of signal peak power of 650 kW, compared to the pump laser in the same cavity without the IOPO, was achieved. A conversion efficiency of 44% with respect to the 1064-nm pump beam and 3.8% with respect to diode pump energy was demonstrated. Received: 15 October 2002 / Revised version: 19 February 2003 / Published online: 16 April 2003 RID="*" ID="*"Corresponding author. Fax: +48-22/666-8950, E-mail: wzendzian@wat.edu.pl     

Economic comparison between adsorption and compression heat pumps

Adsorption and electric heat pumps have been compared for domestic heating and cooling for three Italian cities: Messina, Rome and Milan. The daily energy needs based on the characteristics of a flat and on the meteorological data of the cities have been calculated. From heating and cooling efficiencies of the electric and adsorption heat pumps the electric and gas energy consumption have been evaluated and compared. Finally, the annual cost of the electric heat pump has been estimated and from this, the maximum available cost of the adsorption machine is presented for each city.The final results show that adsorption heat pumps represent an energy saving machine with a good economic competitivity with respect to the traditional system.     

Three-level operation of a diode-bar-pumped Yb:S-FAP laser

We present an all solid-state Yb:S-FAP laser system running on the three-level laser transition at 985 nm. The pump source was a high fill-factor laser diode bar, with the output reformatted using a two-mirror beamshaping system to produce a rectangular pump beam that focused to a square spot. A nearly on-axis multipassing system was used to obtain four pump passes through a 1.6 mm Yb:S-FAP laser crystal. Gain-switched three-level laser output was achieved with an efficiency of 4.3% with respect to incident pump power. Electro-optic Q-switching produced 0.12 mJ pulses for a pump pulse energy of 11 mJ. Intra-cavity second-harmonic generation yielded a maximum pulse energy at 492.5 nm of 12 μJ.     

燃气机热泵的热电冷三联供系统分析

提出了一个燃气机热泵的热电冷三联供系统，并介绍其组成．为分析燃用不同气体燃料的系统热力学完善程度，提出了标准气耗的概念．对热电冷三联供系统的分析结果表明，该系统的一次能源利用率可达１．４９，比热电冷分供高一倍，标准气耗则降低一半左右．     

20 W passively cooled single-mode all-fiber laser at 2.8 μm

A maximum output power of 20.6 W at 2.825 μm from an erbium-doped all-fiber laser is reported, which we believe is the highest output power for this laser transition in single-mode operation. The slope efficiency of the passively cooled laser was up to 35.4% with respect to the absorbed pump power. Accounting for an estimated round-trip intracavity loss of 1.3 dB, we calculated a theoretical conversion efficiency of 39.5%, which is 15% higher than the Stokes efficiency of 34.3%. We believe this is the first experimental confirmation of the predicted pump energy recycling for this fiber laser. The narrow laser linewidth varied from 0.09 to 0.16 nm from low to maximum output power.     

All-Solid-State Nd:YAG Laser Operating at 1064nm and 1319nm under 885nm Thermally Boosted Pumping

We report a high-effciency Nd：YAG laser operating at 1064 nm and 1319nm, respectively, thermally boosted pumped by an all-solid-state Q-switched Ti：sapphire laser at 885 nm. The maximum outputs of 825.4 m W and 459.4mW, at 1064nm and 1319nm respectively, are obtained in a 8-ram-thick 1.1 at.% Nd：YAG crystal with 2.1 W of incident pump power at 885nm, leading to a high slope efficiency with respect to the absorbed pump power of 68.5% and 42.0%. Comparative results obtained by the traditional pumping at 808nm are presented, showing that the slope efficiency and the threshold with respect to the absorbed pump power at 1064nm under the 885nm pumping are 12.2% higher and 7.3% lower than those of 808rim pumping. At 1319nm, the slope efficiency and the threshold with respect to the absorbed pump power under 885nm pumping are 9.9% higher and 3.5% lower than those of 808 nm pumping. The heat generation operating at 1064 nm and 1319 nm is reduced by 19.8% and 11.1%, respectively.     

Water-Spray-Cooled Quasi-Isothermal Compression Method: Water-Spray Flow Improvement

Water-spray-cooled quasi-isothermal compressed air energy storage aims to avoid heat energy losses from advanced adiabatic compressed-air energy storage (AA-CAES). The compression efficiency increases with injection water spray. However, the energy-generated water spray cannot be ignored. As the air pressure increases, the work done by the piston and the work converted into heat rise gradually in the compression process. Accordingly, the flow rate of the water needed for heat transfer is not a constant with respect to time. To match the rising compression heat, a time sequence of water-spray flow rate is constructed, and the algorithm is designed. Real-time water-spray flow rate is calculated according to the difference between the compression power and heat-transfer power. Compared with the uniform flow rate of water spray, energy consumption from the improved flow rate is reduced.     

The impact of heat pumps on global warming and ozone depletion

The heat pump, a proven and reliable technology, has the potential to reduce primary energy consumption and the corresponding CO₂-emissions for heating and cooling in domestic, commercial and industrial applications. The basic principles of heat pump technology and the anthrogenic CO₂-formation under the given energy supply and demand situation in Europe and the related impact on global warming are described.An analysis of the energy flow between primary energy exploitation and the useful energy of different heating systems clearly demonstrates the ability of electric heat pumps to reduce primary energy consumption in Europe between 15 and 50%, compared with oil- and gas-heating systems. The corresponding reduction of CO₂-emissions will be between 20 and 60% and up to 85% of other pollutants.The present status of alternative working fluids which do not contribute to ozone depletion is presented and the direct (working fluids) and indirect (energy consumption) impact of different heat pumps on the greenhouse effect is discussed.     

Absorption cycles. A review with regard to energetic efficiency

The improvement of energy conversion systems in order to decrease consumption of primary energy and to minimize negative impact on the environment which originates from industries with large cooling and heating demand is mandatory. We want to review the potential of absorption heat pump technology in this respect. Absorption systems are compared to conventional compression systems with regard to the consumption of primary energy. Different areas of application such as air-conditioning, refrigeration, heating, combined cooling and heating, and process heat recovery are treated. Absorption systems have a large potential for energy saving, especially when they are operated by heat from cogeneration systems or, of course, by waste heat. But even direct-fired systems can compete with compression machinery: highly efficient cycles which perform far better than comparable conventional machines are in development.     

新型高效机械压缩式热泵蒸发系统的设计及实验研究

根据化工行业的环保以及节能要求,提出了一套处理废液回收的新型高效热泵蒸发系统.不同于以往的化学及物理方法,采用了热泵蒸发处理技术.系统以板式换热器作为蒸发器,采用升膜蒸发的方式,实现废液的浓缩回收.系统运行结果表明:设计方案可行,能够实现预期效果,符合环保及节能的要求.     

Utilization of geothermal waters for heating by heat pumps

This paper treats the solution to the problem of the connection of heat exchanger and heat pumps in geothermal district heating systems. A numerical solution for the theoretical Rankine heat pump cycle is presented to determine the thermodynamic process efficiency as a criterion of quality of energy flow in the process of its transformation. This allows a reduction in the losses caused by irreversibility of real processes and saves energy. The results in graphical form are used in practice for technical and economic optimization of various geothermal heating systems employing heat pumps.     

谐振电机耦合型双效斯特林燃气热泵系统研究

针对当前国家大力推行清洁能源技术和煤改气政策的供暖现状,本文探索了一种双效斯特林燃气热泵系统.全文基于热声学观点对系统进行了理论研究,并采用SAGE程序对其进行数值模拟和优化设计.计算表明,当加热、供热和冷端温度分别为923 K、333 K和273 K时,系统可获得的泵热量为7000 W,COPh为 1.79,系统?效...     

低品位热能有机朗肯循环发电技术进展

有机朗肯循环发电技术是基于有机朗肯循环(Organic Rankine Cycle, ORC),利用低沸点有机工质,将低品位的余热资源转换为高品位的电能的先进技术,能够有效提高能源的利用率,减少能源损失。针对工业过程中大量中低温余热受到各种限制难以回收利用难题,全面综述了有机工质朗肯循环低温余热发电技术现状和进展,具体包括循环工质、关键设备、系统优化以及产业应用等。分析表明,该技术可广泛用于地热能、生物质能、太阳热能等领域的低品位热能开发与利用,其产业化推广将有效提高普遍存在的低温余热利用效率。     

航天器变速热泵回路的技术优势分析

在保证航天器废热排放量的基础上,通过计算对比分析了固定转速热泵回路热控系统和变速热泵回路热控系统的耗电量,结果证明后者比前者节能20％左右。综合分析还表明:变速热泵可以实现软启动,对航天器上的电网无冲击,对其它用电设备无干扰;可以实现快速制冷和供热;控温精度高,回舱流体温度波动小;可靠性高,寿命长;脉动噪声小;可以实现无级调速,具有热负荷调节范围宽等技术优势。变速热泵技术已经发展成熟,具备了在航天器上应用的条件。     

Highly efficient in-band pumped Er:YAG laser with 60 W of output at 1645 nm

A high-power Er:YAG laser that is in-band pumped by a high-power cladding-pumped erbium-ytterbium codoped fiber laser operating at 1532 nm is reported. The Er:YAG laser produced 60.3 W of continuous-wave output at 1645.3 nm in a beam with M2 approximately equal to 3 for 82 W of incident pump power and 20 W of TEM00 output with M2 < 1.2 for 32.4 W of incident pump power. The slope efficiency with respect to incident pump power at pump powers of >20 W was approximately 81%. In the Q-switched mode of operation, a slightly modified resonator configuration incorporating an electro-optic Q switch produced pulses of approximately 4 mJ energy and approximately 100 ns (FWHM) duration, corresponding to a peak power of approximately 42 kW at a repetition rate of 1 kHz for an incident pump power of 16.8 W. The prospects for further improvement in continuous-wave and Q-switched performance are discussed.     

Highly efficient continuous-wave composite Nd:YAG laser at 1,112 nm under diode pumping directly into the emitting level

We present an efficient, high-brightness laser at 1,112 nm by combining the direct pumping technique with an 885 nm laser diode and the composite crystal. Output power as high as 12.8 W at 1,112 nm is achieved under 22.2 W of absorbed pump power and it yields an optical-to-optical efficiency of 57.7 % and a slope efficiency of 64.0 % with respect to the absorbed pump power. To the best of our knowledge, both of these optical-to-optical and slope efficiencies with respect to the absorbed pump power are the highest values ever reported for 1,112 nm Nd:YAG lasers. Modeling of the temperature rise and stress induced in the laser crystals, with and without the undoped cap, and employing the pump at 808 and 885 nm are performed, respectively. Contributions of the composite crystal geometry and of the pump at 885 nm to lowering the threshold power, enhancing the optical-to-optical and the slope efficiencies with respect to the absorbed pump power are discussed, respectively.     

温库边界对布朗热机性能的影响

研究了单势垒锯齿势中,布朗粒子在外力和空间周期温度场作用下构成的布朗热机的热力学性能.考虑布朗粒子动能变化以及高、低温库之间热漏引起的热流.用Smoluchowski方程描述粒子在黏性介质中的动力学特性,推导出高、低温库的热流以及热机功率和效率的解析表达式.通过数值计算分析势垒高度、外力和温库边界对热机性能的影响.研究表明:由于动能变化和热漏引起的不可逆热流的存在,布朗热机为不可逆热机,热机的功率效率特性为一闭合的关系曲线;势垒边界与温库边界重合时,热机的功率达到最大值;通过改变温库边界的位置,可以在一定范围内提高热机的效率,但同时减小了热机的输出功率.