CN-115688631-B - Cooling water supply and demand matching evaluation method for ship self-flowing cooling water system

Abstract

The invention discloses a cooling water supply and demand matching evaluation method of a ship self-flowing cooling water system, which is based on realizing the cooling water supply and demand matching evaluation of the self-flowing cooling water system under a steady-state working condition, combines dynamic description and pull-type inverse transformation of corresponding processes of the self-flowing cooling water system in a corresponding s domain, directly obtains mathematical description of the cooling water supply and demand of the self-flowing cooling water system at different moments, and further completes the evaluation of the dynamic cooling water supply and demand matching of the self-flowing cooling water system, thereby being capable of rapidly grasping the cooling water supply and demand matching of the self-flowing cooling water system under the steady-state and dynamic working conditions without a great deal of modeling and simulation work and being beneficial to comprehensively evaluating the design performance of the self-flowing cooling water system by designers of the self-flowing cooling water system.

Inventors

• LI XIANLING
• KE ZHIWU
• LV WEIJIAN
• DAI LU
• TAO MO
• FENG YI
• ZHENG WEI
• ZOU HAI
• CHAI WENTING
• XIONG QING
• WANG WEI
• WU JUN

Assignees

• 中国船舶重工集团公司第七一九研究所

Dates

Publication Date

20260505

Application Date

20221114

Claims (6)

1. 1. The cooling water supply and demand matching evaluation method of the self-flowing cooling water system of the ship is characterized by comprising the following steps of: Obtaining steady-state cooling water supply flow and steady-state cooling water demand flow passing through the self-flow cooling water system at different navigational speeds, and respectively determining a first navigational speed of the ship and a second navigational speed of the ship before and after the working condition of the self-flow cooling water system changes; based on the steady-state cooling water demand flow, the first ship navigational speed and the second ship navigational speed, the cooling water demand change quantity when working conditions change is constructed The method comprises the steps that a first expression in a domain is subjected to pull-type inverse transformation to obtain dynamic cooling water demand flow when working conditions change; the first expression specifically includes: Wherein, the As a first time constant, the first time constant, The required flow of the steady-state cooling water for the second ship navigational speed, The required flow of the steady-state cooling water for the first ship navigational speed, The cooling water requirement variable quantity is the cooling water requirement variable quantity when the working condition is changed; the expression of the dynamic cooling water demand flow when the working condition changes is specifically as follows: Wherein, the In order to be able to take time, The dynamic cooling water demand flow rate is the dynamic cooling water demand flow rate when the working condition changes; Based on the steady-state cooling water supply flow, the first ship navigational speed and the second ship navigational speed, constructing the cooling water supply variable quantity when the working condition is changed to be at A second expression in the domain, and carrying out pull-type inverse transformation on the second expression to obtain dynamic cooling water supply flow when the working condition changes; the second expression is specifically: Wherein, the For the second time constant to be a second time constant, For the third time constant to be a third time constant, Supplying a flow rate for the steady-state cooling water of the second ship at the navigational speed, The first vessel is supplied with steady-state cooling water flow, The variable quantity is supplied to the cooling water when the working condition changes; the expression of the dynamic cooling water supply flow rate when the working condition changes is specifically as follows: Wherein, the In order to be able to take time, Supplying flow for the dynamic cooling water when the working condition changes; And judging that the dynamic cooling water supply flow is not smaller than the dynamic cooling water demand flow at different moments, wherein the self-flow cooling water system has dynamic cooling water supply and demand matching property, otherwise, the system does not have dynamic cooling water supply and demand matching property.
2. 2. The method of evaluating of claim 1, further comprising, after obtaining the steady-state cooling water supply flow and steady-state cooling water demand flow through the self-flowing cooling water system at different navigational speeds: And under different navigational speeds, judging that the steady-state cooling water supply flow is not smaller than the steady-state cooling water demand flow, wherein the self-flow cooling water system has steady-state cooling water supply and demand matching property, otherwise, the system does not have steady-state cooling water supply and demand matching property.
3. 3. The method of evaluating according to claim 1, wherein the steady-state cooling water supply flow is obtained based on a principle that a static pressure difference of an inlet and an outlet of the self-flowing cooling water system at different ship speeds is balanced with a sum of an on-way resistance and a local resistance.
4. 4. The evaluation method according to claim 1, wherein the steady-state cooling water demand flow rate acquisition method comprises: obtaining the outlet temperature of cooling water at different navigational speeds according to a heat exchange balance equation in the condenser; based on the cooling water outlet temperature and the cooling water inlet temperature under different navigational speeds, obtaining the cooling water inlet-outlet temperature difference under different navigational speeds; And acquiring the steady-state cooling water demand flow based on the cooling water inlet-outlet temperature difference under different navigational speeds.
5. 5. The method of evaluating according to claim 4, wherein the equation of heat exchange balance in the condenser is specifically: Wherein, the In order to obtain the total cooling requirement of the self-flowing cooling water system under different navigational speeds according to the overall design of the ship power plant, Is the heat transfer area; the heat transfer coefficient in the condenser is the same as that in the condenser at different navigational speeds; to thermally measure fluid temperature; The inlet temperature of cooling water; for the cooling water outlet temperature at different navigational speeds, Is the navigational speed of the ship.
6. 6. The assessment method according to claim 1, wherein said operating condition changes as a process of changing from one steady state of operation to another steady state of operation.

Description

Cooling water supply and demand matching evaluation method for ship self-flowing cooling water system Technical Field The invention relates to the technical field of ship cooling system design, in particular to a cooling water supply and demand matching evaluation method of a ship self-flowing cooling water system. Background The cooling water system is an essential important link of the ship and is an important component of the ship power system. In order to reduce the problems of scaling and corrosion, the current advanced ships all adopt a central cooling water system, and the working principle of the central cooling water system is that a sea water pump is used for conveying sea water into the central cooling system to cool low-temperature fresh water, and the cooled low-temperature fresh water is used for cooling high-temperature fresh water of a main diesel engine cylinder sleeve and a cylinder cover of the ship, and various coolers and power generation diesel engine cylinder sleeves. For a central cooling water system, the main operating cost of the system is the energy consumption of a seawater pump. In order to reduce the operation energy consumption of the system, a self-flowing cooling water system is developed, the system inherits all the advantages of a central cooling water system, and meanwhile, the defects of the system are overcome. When the cooling water supply flow rate of the self-flow cooling water system is larger than the required flow rate, the self-flow cooling process can be performed, otherwise, a water pump is started to perform auxiliary cooling. Therefore, it is needed to evaluate the supply and demand matching of the cooling water of the self-flowing cooling water system of the ship so as to ensure that the designed self-flowing cooling water system can meet the cooling requirement in the target navigational speed range under the steady-state working condition and the dynamic working condition. Disclosure of Invention Aiming at the cooling water supply and demand matching evaluation requirement of the self-flowing cooling water system in the design process, the invention aims to provide the cooling water supply and demand matching evaluation method of the self-flowing cooling water system of the ship, which can rapidly evaluate the dynamic cooling water supply and demand matching of the self-flowing cooling water system of the ship on the basis of accounting the steady-state cooling water supply and demand matching of the self-flowing cooling water system. In order to achieve the above object, the present invention provides a cooling water supply and demand matching evaluation method for a self-flowing cooling water system of a ship, comprising: Obtaining steady-state cooling water supply flow and steady-state cooling water demand flow passing through the self-flow cooling water system at different navigational speeds, and respectively determining a first navigational speed of the ship and a second navigational speed of the ship before and after the working condition of the self-flow cooling water system changes; Based on the steady-state cooling water demand flow, the first ship navigational speed and the second ship navigational speed, constructing a first expression of the cooling water demand change quantity in an s domain when the working condition changes, and carrying out pull-type inverse transformation on the first expression to obtain the dynamic cooling water demand flow when the working condition changes; Constructing a second expression of the cooling water supply variable quantity in an s domain when the working condition is changed based on the steady-state cooling water supply flow, the first ship navigational speed and the second ship navigational speed, and carrying out pull-type inverse transformation on the second expression to obtain the dynamic cooling water supply flow when the working condition is changed; And judging that the dynamic cooling water supply flow is not smaller than the dynamic cooling water demand flow at different moments, wherein the self-flow cooling water system has dynamic cooling water supply and demand matching property, otherwise, the system does not have dynamic cooling water supply and demand matching property. Further, after obtaining the steady-state cooling water supply flow and the steady-state cooling water demand flow through the self-flowing cooling water system at different navigational speeds, the method further comprises: And under different navigational speeds, judging that the steady-state cooling water supply flow is not smaller than the steady-state cooling water demand flow, wherein the self-flow cooling water system has steady-state cooling water supply and demand matching property, otherwise, the system does not have steady-state cooling water supply and demand matching property. Further, the first expression specifically includes: Where α is a first time constant, m n(v2) is a second ship speed steady-state coo