ABSTRACT
Central heating pipe network is a fluid network, which is similar to electrical network, complying with Kirchhoff ’s current and voltage laws, and the slip flow, pressure drop and pipeline resistance coefficient characteristics analogous to electric current branch network, voltage and resistance. For any network, you can get the basic model of central heating pipe network hydraulic conditions [4]
Aqg = qj (1)
Bfp = 0 (2)
p = S|qg|qg + ρgh − ρgH (3)
A: tubes gateway linking matrix of n × m matrix of order, it is the sole representative of the topology of the network, its rank is n qg: pipe flow vector qg1, qg2, …, qgm: the 1, 2…pipe sections flow, m3/h; qj: net flow vector node (qj1, qj2, …, qjn, m3/h;)
1 INTRODUCTION
The late 1970s and early 1980s, on the basis of China’s research on water heating system working conditions, to study the thermal expansion conditions, and on the relationship between hydraulic conditions and thermal conditions, giving the lay of the conclusions: hydraulic systems are the important cause of system imbalance Enthusiasm [1]. Currently, Central heating system exist prevailing hydraulic imbalance generally, the actual operation of the heating system in each unit of heat users of heating medium flow heating area does not match with the design flow, which results in nearly cold thermal heat far imbalances [2]. To achieve a stable thermal condition of the heating system reasonably, it must be a stable hydraulic conditions and reasonable flow distribution. Typically, initial adjustment is before the central heating system is running (or running), so that each user to achieve the desired flow conditions (or design conditions). But the initial adjustment can only adjust the central heating system deployed by the heat load evenly, thereby enabling each user’s average temperature to reach consensus. To ensure the central heating system throughout the heating period are running well, on-demand heating, also need running adjustment, at any time based on the outdoor temperature changes, and user selfregulate, regulate water temperature and flow pipe network [3]. Therefore, researching the hydraulic characteristics of urban centralized heating hot water pipe network in different operation mode,
qj1, qj2, …, qjn: the traffic nodes, m3/h; Bf: the basic loop matrix pipe network for (m − n) × m matrix; p: pipe pressure drop vector; p1, p2, …, pm: the pressure drop tube segment, Pa; S: pipe resistance characteristics coefficient matrix (m-order diagonal matrix); |qg|: qg absolute value of (m-order diagonal matrix), |qg| = diag{|qg1|,|qg2|,…,|qgm|}, m3/h; ρ: fluid density, m/s2; g: acceleration due to gravity, m/s2; h: Vector pipe segment elevation difference of two nodes, h = (h1, h2,…, hm), m; H: Pump head vector pipe section, H = (H1, H2, …, Hm), m.
