基于太阳能热泵的LPG气化系统研究

发布时间：2018-01-09 12:14

本文关键词：基于太阳能热泵的LPG气化系统研究　出处：《华北电力大学》2015年博士论文　论文类型：学位论文

【摘要】：随着常规能源的日渐枯竭和环境问题的日益严峻,作为清洁能源的液化石油气(LPG)和可再生能源的太阳能受到中国政府的日益重视和青睐。LPG管道集中供应作为天然气管网的补充在国内有着大量应用,而太阳能热泵技术作为太阳能利用的一种较成熟的应用方式,近几十年来得到了迅速发展。在LPG管道集中供应系统中,传统的LPG气化方式能耗高,而太阳能热泵技术能够高效地制取中高温热水,可作为液态LPG的气化热源。基于解决LPG气化高能耗问题和拓宽太阳能热泵技术应用领域的思想,我们提出了一种新型的基于太阳能热泵的LPG气化(Direct Expansion Solar Assisted Heat Pump Vaporization, DX-SAHPV)系统,该系统主要由直膨式太阳能热泵(DX-SAHP)、蓄热水箱、辅助热源及气化器组成,将太阳能热泵技术应用到城市燃气领域,提高了太阳能热泵的全年利用率。本文利用热量守恒定律、质量守恒定律、气液相平衡原理和SRK状态方程建立了钢瓶内LPG自然气化模型。将钢瓶内的气相LPG和液相LPG分别视为实际气体和实际溶液,在模型中考虑了由于非共沸混合物的特性导致的LPG成分变化及其对LPG温度、压力、气化潜热、密度等物性参数的影响。以此为基础,在给定初始液相LPG成分和外界参数的条件下,对充装LPG的ysp-50型钢瓶内的LPG自然气化特性进行了数值模拟,并通过已有的实验结果进行验证。研究发现,自然气化过程中,气、液两相LPG的成分瞬时变化,LPG温度急剧下降后基本维持在一定值,气相中低沸点成分的减少和温度的降低导致了LPG压力的下降。对比模拟结果和实验结果及实际现象,建立的LPG自然气化模型具备较高的数值计算精度。在自然气化模拟的基础上确定了定用气量和变用气量时单个钢瓶的自然气化能力。同时,进行了居民燃气用户用气量和用气负荷波动性的分析和计算。该部分工作可以为DX-SAHPV系统的合理设计与性能研究提供客观依据。为了使DX-SAHP具有良好的热经济性,利用有限时间热力学理论建立了DX-SAHP的热力学模型。以单位成本热负荷最大为目标函数,推导出了最佳设计参数(如蒸发温度、冷凝温度、换热器面积比等)的理论表达式。同时,考察了环境参数、换热器性能参数、经济性参数等对DX-SAHP优化特性和最优设计参数的影响。研究结果表明,DX-SAHP运行时,比供热率应小于单位成本热负荷最大时对应的比供热率值,以避免DX-SAHP的供热性能系数和热经济性出现恶化；内不可逆性、单位面积换热器投资成本、压缩机投资和运行成本、集热面太阳辐射强度、集热／蒸发器吸收率和透过率的乘积、负载水温对DX-SAHP的优化特性影响较大,当其它参数不变,这些参数分别变化10%时,最佳热经济性的变化超过2%。根据LPG自然气化特性、用户用气负荷和气象条件波动特性,研究了DX-SAHPV系统的六种运行模式和运行原理。以DX-SAHP热经济性优化为基础,采用年费用最小、一次能源节省率最大和全球变暖影响指数最小作为优化目标,针对DX-SAHPV系统的供气要求,建立了系统的多目标优化设计模型。利用该模型分析了系统中DX-SAHP和辅助热源的最优气化负荷分配、各部分最优设计参数和最优辅助热源形式,制定了DX-SAHPV系统的优化设计方法。建立了DX-SAHPV系统的动态仿真数学模型,制定了系统中DX-SAHP、辅助热源和气化器的启／停条件,得出各运行模式的控制策略,进而得出不同运行工况下蓄热水箱数学模型的具体表达形式。在所建立的LPG自然气化模型、多目标优化设计、系统仿真模型及控制策略基础上,以规模为1000户居民的住宅小区为供气对象,深入研究了DX-SAHPV系统在北京地区的全年动态运行性能。此外,改变应用地区的地理参数和气象条件,模拟预测分析了系统在全国几个不同太阳能资源等级典型地区的运行性能。
[Abstract]:With the gradual depletion of conventional energy and the increasingly serious environmental problems, as liquefied petroleum gas (LPG) clean energy and renewable energy solar China government pay more and more attention and favor.LPG pipeline as a supplement to focus on the supply of natural gas pipeline network in the country has a large number of applications, and the solar heat pump technology as a kind of solar energy utilization. The mature application, in recent decades has been developing rapidly. Focus on LPG pipeline supply system, the traditional way of high energy consumption of LPG gasification, and solar heat pump technology can efficiently produce high temperature hot water, can be used as heat source for gasification of liquid LPG. To solve the LPG gasification of high energy consumption problem and broaden the field of application of solar heat pump technology based on the idea, we propose a new type of solar heat pump based on LPG gasification (Direct Expansion Solar Assisted Heat Pump Vaporization, DX-SA HPV) system, the system is mainly composed of DX-SAHP (DX-SAHP), storage tank, auxiliary heat source and gasification device, the application of solar heat pump technology to city gas field, improve the utilization rate of the solar heat pump. Based on the law of conservation of energy, the law of mass conservation principle and SRK state equation of cylinder LPG gasification model was established for gas-liquid equilibrium. The cylinder gas phase and liquid phase LPG LPG are regarded as the actual gases and solutions, in the model of senior high school entrance examination considered due to the non azeotropic mixture characteristics lead to LPG component changes and the LPG temperature, pressure, latent heat of vaporization, density and other physical parameters on the basis, given the initial liquid phase LPG components and external parameters under the condition of natural LPG gasification characteristics of ysp-50 type cylinder for filling in LPG was simulated, and the existing experimental results are tested Card. The study found that the natural process of gasification, gas, liquid component instantaneous change of LPG, LPG after a sharp drop in temperature is maintained at a certain value, reduce the low boiling point components in gas phase and temperature led to decreased LPG pressure. Comparing the simulation results and the experimental results and the actual phenomenon, the natural LPG gasification model the establishment of a higher numerical accuracy. On the basis of natural gasification simulation is determined on the fixed gas and natural gas gasification ability of single cylinder. At the same time, the residents of gas users and gas analysis and calculation of gas load fluctuates. This work can provide the objective basis for the study of rational design DX-SAHPV system and performance. In order to make the DX-SAHP has good thermal economy, the thermodynamic theory of a thermodynamic model of DX-SAHP using finite time. The unit cost of heat load as the goal The function, deduced the optimum design parameters (such as evaporation temperature, condensation temperature, heat exchanger area ratio) the theoretical expression. At the same time, effects of environmental parameters, change the performance parameter of heat exchanger, the economic impact of parameters on the optimization characteristics and the optimal design parameters of DX-SAHP. The results show that DX-SAHP is running the heating rate should be less than the unit cost of heat load corresponds to the maximum ratio of heating rate, to avoid heating performance coefficient and thermal economy of DX-SAHP deteriorated; internal irreversibility, unit area heat exchanger compressor investment cost, investment and operation cost, heat collecting surface solar radiation, heat collector / evaporator absorption rate and the transmittance of the product, greater impact load optimization characteristics on DX-SAHP constant temperature, when the other parameters, these parameters were changed in 10% when the economy changes the best heat more than 2%. LPG according to the characteristics of natural gas, gas users with negative Load and meteorological conditions on the wave characteristics of six kinds of operation mode and operation principle of the DX-SAHPV system. The DX-SAHP thermal efficiency optimization as the foundation, the minimum annual cost, an energy saving rate and the impact of global warming index minimum as the optimization goal, according to the requirements of the DX-SAHPV system of the gas supply, a multi-objective optimization model analysis of the gasification system. Optimal load allocation DX-SAHP and auxiliary heat source system by using the model, the optimal design parameters and the optimum auxiliary heat source form, the optimal design method for the DX-SAHPV system. A dynamic simulation model of DX-SAHPV system, developed a system of DX-SAHP, start / stop condition and auxiliary heat source the gasifier, the control strategy for each operation mode, then obtains the specific forms of expression of the mathematical model of the heat storage tank under different operating conditions in the establishment of the LPG. Vaporization model, multi-objective optimization design, model and control strategy based on system simulation, with the scale of 1000 households in the residential supply object, in-depth study of the dynamic performance of DX-SAHPV system in the Beijing area. In addition, change the application areas of the physical parameters and meteorological conditions, simulation and prediction of performance analysis the system in several typical regions of different levels of solar energy resources.

【学位授予单位】：华北电力大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU83

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