CN105243235A - Heat storage volume determining method for solar hot water heating system - Google Patents

Abstract

The invention discloses a heat storage volume determining method for a solar hot water heating system. Mainly, with an energy flow balance relationship of a solar heating system as a constraint condition, heat storage system volume as an optimized decision variable and the lowest annual energy consumption of a supplementary heat source as an optimized objective function, an optimization model is established; and the optimal heat storage volume of the solar hot water heating system is finally determined; and the problem of different optimal heat storage volume caused by the differences in different regions, different building types and different building parameters is effectively solved, so that a good energy-saving role is put into a play.

Description

Solar hot water heating system accumulation of heat volume defining method

Technical field

The invention belongs to technical field of solar utilization technique, particularly a kind of solar hot water heating system accumulation of heat volume defining method.

Background technology

Sun power is the main source of all energy on the earth, and it is inexhaustible, non-harmful clean energy resource, is also the most promising energy that after 21 century, the mankind can expect.China is vast in territory, and the area that the sunshine-duration in year is greater than 2000 hours accounts for 2/3 of national area, be in utilize sun power more favourable region in.

But sun power is the thin energy, and the energy resource density of its earth surface is lower.And solar radiation heat has season, rule change round the clock, strongly affecting simultaneously also by the enchancement factor such as rain or shine sexual intercourse, therefore solar radiant heat measurer has very large instability.Because solar energy heating and building heating thermal load demands have undulatory property, and solar energy heating and space heating load demand have the features such as asynchronism, as shown in Figure 1, cause utilizing sun power, intermittence and the unreliability problem of sun power must be solved.Arranging regenerative apparatus in solar energy utilization system is one of most effective method solved the problem.Facts have proved, regenerative apparatus has the meaning of particular importance to the utilization ratio improving sun power.

The method of the solar heating accumulation of heat of normal employing has, the forms such as hot water storage tank accumulation of heat, phase-change material accumulation of heat, soil thermal storage.What the most often adopt in actual solar heating engineering is the mode of hot water storage tank accumulation of heat, and as shown in Figure 2, this hold over system form, by main apparatus components such as heat collector 1, water tank 2 and auxiliary thermal sources 3, meets Indoor Thermal demand by the form such as thermal-arrest, accumulation of heat.

But, accumulation of heat volume is crossed conference and is caused water tank temperature to be starkly lower than design supply water temperature, system needs the long-time auxiliary thermal source that starts to carry out heat supply, reduce the energy saving of system, accumulation of heat volume is too small, and heat collector return water temperature can be caused higher, reduce the heat-collecting capacity of heat collector, the energy saving of system can be reduced equally.Visible, how to determine the volume of hot water storage tank, become the important step of solar hot water heating system design.Point out in national standard " solar-heating heating engineering technical manual " GB50495-2009, the heat storage water tank of the corresponding every square metre of solar thermal collector daylighting area of all kinds of solar-heating heating system should be chosen according to table 1, but due to the difference of different regions, different building type and different architectural modulus, cause best accumulation of heat volume different, prior art does not provide accumulation of heat volume defining method accurately.

The heat storage water tank of table 1 solar thermal collector daylighting area

Summary of the invention

The object of the invention is to: for above-mentioned Problems existing, provide one can be minimum for optimization object function with the annual energy consumption of auxiliary thermal source, obtain the defining method of the optimum accumulation of heat volume of solar hot water heating system.

The object of the invention is to be achieved through the following technical solutions: a kind of solar hot water heating system accumulation of heat volume defining method, it is characterized in that: closing with solar energy heating system energy mobile equilibrium is constraint condition, hold over system volume is Optimal Decision-making variable, the annual energy consumption of auxiliary thermal source is minimum is optimization object function, set up Optimized model, be specially:

A), constraint condition

1. system by time heat balance relation:

H moment heat collector direct heating amount can be expressed as:

$Q_{j.g}\left(h\right)=\left\{\begin{array}{cc}{Q}_j\left(h\right),& Q_f\left(h\right)>Q_j\left(h\right)\\ Q_f\left(h\right),& Q_f\left(h\right)\≤Q_j\left(h\right)\end{array}\right.$

The thermal balance equation of h moment water tank waste heat amount can be expressed as:

The h moment can be expressed as (not enough heat demand will by amount of stored heat and auxiliary thermal source heat supply) by heat not enough after solar energy heating direct heating:

$Q_{g.q}\left(h\right)=\left\{\begin{array}{cc}{Q}_j\left(h\right)-Q_f\left(h\right),& Q_f\left(h\right)-Q_j\left(h\right)<0\\ 0,& Q_f\left(h\right)-Q_j\left(h\right)\&GreaterEqual;0\end{array}\right.$

The instant amount of stored heat of h moment water tank can be expressed as:

H moment auxiliary thermal source heating load can be expressed as:

In formula: Q _jh () is h moment heat collector heat-collecting capacity,

$Q_j\left(h\right)={\&Integral;}_{h-1}^h\frac{3600{{\mathrm{\&eta;}}_h}^{+}\&CenterDot;A_{r,w}/cos\mathrm{\&theta;}\&CenterDot;I\left(h\right)}{1000},$ kJ；

θ is heat collector mounted angle, °;

I (h) is the solar irradiation intensity of h moment dip plane, W/m ²;

Q _fh () to be heated institute's heat requirement for the h moment, kJ;

2. annual energy input (calculating with electricity):

In formula, Q (V) is annual energy input (calculating with electricity), kWh;

COP (h) is the coefficient of performance in heating of h moment air source heat pump, W/W;

3. water tank water temperature upper limit constraint:

t≤t _max

In formula, t _maxfor the maximum water temperature of water tank, DEG C;

B), objective function

The annual energy consumption of auxiliary thermal source is minimum:

Solar hot water heating system accumulation of heat volume defining method of the present invention, it, by described Optimized model, utilizes MATLAB software programming solver to solve, is specially:

A), according to architectural modulus and hourly weather data, customer charge demand is calculated;

B) the accumulation of heat volume of solar hot water heating system, is tentatively determined by heat collector photo-thermal area and setting angle;

C), in conjunction with hourly weather data and equipment thermodynamic property, draw heat-collecting capacity, form system energy mobile equilibrium relation;

D), according to auxiliary thermal source by time consumes power, calculate building year energy consumption;

E), judge building year energy consumption whether be less than setting value, if year energy consumption be less than setting value, then obtain the optimum accumulation of heat volume of solar hot water heating system, and export, if year, energy consumption was greater than setting value, then return step b), redefine the accumulation of heat volume of solar hot water heating system.

It is constraint condition that the present invention is mainly closed with solar energy heating system energy mobile equilibrium, hold over system volume is Optimal Decision-making variable, the annual energy consumption of auxiliary thermal source is minimum is optimization object function, set up Optimized model, finally determine the optimum accumulation of heat volume of solar hot water heating system, efficiently solve the difference because of different regions, different building type and different architectural modulus, and the problem that the best accumulation of heat volume caused is different, thus serve good energy-conserving action.

Accompanying drawing explanation

Fig. 1 is undulatory property and the asynchronism schematic diagram of solar energy heating and space heating load.

Fig. 2 is the structural representation of existing hot water storage tank accumulation of heat form.

Fig. 3 be the present invention utilize software solve process flow diagram.

Mark in figure: 1 is heat collector, and 2 is water tank, and 3 is auxiliary thermal source.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in detail.

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the technology of the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, and be not used in restriction invention.

Embodiment: a kind of solar hot water heating system accumulation of heat volume defining method, closing with solar energy heating system energy mobile equilibrium is constraint condition, and hold over system volume is Optimal Decision-making variable, and the annual energy consumption of auxiliary thermal source is minimum is optimization object function, set up Optimized model, be specially:

A), constraint condition

1. system by time heat balance relation:

H moment heat collector direct heating amount can be expressed as:

$Q_{j.g}\left(h\right)=\left\{\begin{array}{cc}{Q}_j\left(h\right),& Q_f\left(h\right)>Q_j\left(h\right)\\ Q_f\left(h\right),& Q_f\left(h\right)\&le;Q_j\left(h\right)\end{array}\right.$

The thermal balance equation of h moment water tank waste heat amount can be expressed as:

The h moment can be expressed as (not enough heat demand will by amount of stored heat and auxiliary thermal source heat supply) by heat not enough after solar energy heating direct heating:

$Q_{g.q}\left(h\right)=\left\{\begin{array}{cc}{Q}_j\left(h\right)-Q_f\left(h\right),& Q_f\left(h\right)-Q_j\left(h\right)<0\\ 0,& Q_f\left(h\right)-Q_j\left(h\right)\&GreaterEqual;0\end{array}\right.$

The instant amount of stored heat of h moment water tank can be expressed as:

H moment auxiliary thermal source heating load can be expressed as:

In formula: Q _jh () is h moment heat collector heat-collecting capacity,

$Q_j\left(h\right)={\&Integral;}_{h-1}^h\frac{3600{{\mathrm{\&eta;}}_h}^{+}\&CenterDot;A_{r,w}/cos\mathrm{\&theta;}\&CenterDot;I\left(h\right)}{1000},$ kJ；

θ is heat collector mounted angle, °;

I (h) is the solar irradiation intensity of h moment dip plane, W/m2;

Q _fh () to be heated institute's heat requirement for the h moment, kJ;

2. annual energy input (calculating with electricity):

In formula, Q (V) is annual energy input (calculating with electricity), kWh;

COP (h) is the coefficient of performance in heating of h moment air source heat pump, W/W;

3. water tank water temperature upper limit constraint:

t≤t _max

In formula, t _maxfor the maximum water temperature of water tank, DEG C;

B), objective function

The annual energy consumption of auxiliary thermal source is minimum:

By described Optimized model, according to as shown in Figure 3 solve flow process, utilize MATLAB software programming solver to solve, be specially:

A), according to architectural modulus and hourly weather data, customer charge demand is calculated;

B) the accumulation of heat volume of solar hot water heating system, is tentatively determined by heat collector photo-thermal area and setting angle;

C), in conjunction with hourly weather data and equipment thermodynamic property, draw heat-collecting capacity, form system energy mobile equilibrium relation;

D), according to auxiliary thermal source by time consumes power, calculate building year energy consumption;

E), judge building year energy consumption whether be less than setting value, if year energy consumption be less than setting value, then obtain the optimum accumulation of heat volume of solar hot water heating system, and export, if year, energy consumption was greater than setting value, then return step b), redefine the accumulation of heat volume of solar hot water heating system.

Concrete case row: for three layers, west Sichuan plateau Litang County Hotel Buildings, this gross floors area is about 3000m2, and architectural exterior-protecting construction meets " public building energy design standards ".Utilize Dest load simulation software to calculate, annual building heating load is 142178.56kWh.Building solar energy heating area is 350m ², project adopts air source heat pump as auxiliary thermal source, and heating water return temperature is 50 DEG C, and supply water temperature is 60 DEG C, and supply backwater temperature difference is 10 DEG C.

Utilize hold over system of the present invention to optimize defining method, can calculate optimum accumulation of heat volume is 71m ³, namely accumulation of heat volume index is 203L/m ².Under this volume, auxiliary thermal source power consumption 21667.2kWh.

If according to " the solar-heating heating engineering technical manual " span that (GB50495-2009) provides, get 50L/m respectively ², 100L/m ², 150L/m ².Then can calculate auxiliary thermal source energy consumption is 33488.7kWh, 23256.3kWh, 21967.4kWh, and be all greater than auxiliary thermal source energy consumption under the hold over system volume of optimization of the present invention, visible, the present invention can play good energy-conserving action further.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (2)

1. solar hot water heating system accumulation of heat volume defining method, it is characterized in that: closing with solar energy heating system energy mobile equilibrium is constraint condition, and hold over system volume is Optimal Decision-making variable, the annual energy consumption of auxiliary thermal source is minimum is optimization object function, set up Optimized model, be specially:

A), constraint condition

1. system by time heat balance relation:

H moment heat collector direct heating amount can be expressed as:

$Q_{j.g}\left(h\right)=\left\{\begin{array}{cc}{Q}_j\left(h\right),& Q_f\left(h\right)>Q_j\left(h\right)\\ Q_f\left(h\right),& Q_f\left(h\right)\&le;Q_j\left(h\right)\end{array}\right.$

The thermal balance equation of h moment water tank waste heat amount can be expressed as:

The h moment can be expressed as (not enough heat demand will by amount of stored heat and auxiliary thermal source heat supply) by heat not enough after solar energy heating direct heating:

$Q_{g.q}\left(h\right)=\left\{\begin{array}{cc}{Q}_j\left(h\right)-Q_f\left(h\right),& Q_f\left(h\right)-Q_j\left(h\right)<0\\ 0,& Q_f\left(h\right)-Q_j\left(h\right)\&GreaterEqual;0\end{array}\right.$

The instant amount of stored heat of h moment water tank can be expressed as:

H moment auxiliary thermal source heating load can be expressed as:

In formula: Q _jh () is h moment heat collector heat-collecting capacity,

${Q_j}^{\left(h\right)}={\&Integral;}_{h-1}^h\frac{3600{{\mathrm{\&eta;}}_h}^{+}\&CenterDot;A_{r,w}/cos\mathrm{\&theta;}\&CenterDot;I\left(k\right)}{1000},kJ;$

θ is heat collector mounted angle, °;

I (h) is the solar irradiation intensity of h moment dip plane, W/m ²;

Q _fh () to be heated institute's heat requirement for the h moment, kJ;

2. annual energy input (calculating with electricity):

In formula, Q (V) is annual energy input (calculating with electricity), kWh;

COP (h) is the coefficient of performance in heating of h moment air source heat pump, W/W;

3. water tank water temperature upper limit constraint:

t≤t _max

In formula, t _maxfor the maximum water temperature of water tank, DEG C;

B), objective function

The annual energy consumption of auxiliary thermal source is minimum:

2. solar hot water heating system accumulation of heat volume defining method according to claim 1, is characterized in that: by described Optimized model, utilizes MATLAB software programming solver to solve, is specially:

A), according to architectural modulus and hourly weather data, customer charge demand is calculated;

B) the accumulation of heat volume of solar hot water heating system, is tentatively determined by heat collector photo-thermal area and setting angle;

C), in conjunction with hourly weather data and equipment thermodynamic property, draw heat-collecting capacity, form system energy mobile equilibrium relation;

D), according to auxiliary thermal source by time consumes power, calculate building year energy consumption;

E), judge building year energy consumption whether be less than setting value, if year energy consumption be less than setting value, then obtain the optimum accumulation of heat volume of solar hot water heating system, and export, if year, energy consumption was greater than setting value, then return step b), redefine the accumulation of heat volume of solar hot water heating system.