Comprehensive performance evaluation method for medium-temperature cold water central air-conditioning system

Abstract

The invention belongs to the technical field of air conditioning system evaluation, and relates to a comprehensive performance evaluation method for a medium-temperature cold water central air conditioning system, which comprises the following steps of: 1, constructing an evaluation index system; based on the characteristics of the medium-temperature cold water system, selecting core indexes to construct an evaluation index system; 2, determining the weight through a subjective and objective weighting method; wherein the subjective weighting adopts a 1-9 scale method to construct a judgment matrix, an effective matrix is screened through consistency check, and an initial weight is calculated; the initial weight of objective weighting is corrected according to the dispersion degree of expert scoring data; 3, performing grey relational degree calculation on the to-be-evaluated system, and quantifying the comprehensive performance; according to the method, subjective and objective weighting is combined, and subjective deviation of weight distribution is reduced, so that the influence of subjective preference or data distribution on the weight in comprehensive performance evaluation of the air conditioning system can be avoided, and scientificity and universality of an evaluation result are enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of air conditioning system evaluation, and relates to a comprehensive performance evaluation method for a medium-temperature chilled water central air conditioning system. Background Art

[0002] In the existing building evaluation system, the evaluation of air conditioning systems mostly adopts a single weighting method, such as subjective weighting or objective weighting. Therefore, the existing air conditioning system evaluation methods have problems such as unreasonable weight distribution, high data dependence, and limited applicability. Especially for medium-temperature chilled water central air conditioning systems, due to the technical novelty of medium-temperature chilled water central air conditioning systems, the sample data is insufficient, and it is difficult for the existing air conditioning system evaluation methods to accurately reflect the comprehensive performance of the system. In addition, there is a lack of effective means to handle grey problems in the existing technology. Problems such as incomplete data and unclear distribution laws will reduce the credibility of the evaluation results.

[0003] Therefore, a method or device capable of evaluating the comprehensive performance of a medium-temperature chilled water central air conditioner is needed to solve the above technical problems. Summary of the Invention

[0004] The technical solution adopted by the present invention to solve the technical problems is: a comprehensive performance evaluation method for a medium-temperature chilled water central air conditioning system, comprising the following steps:

[0005] Step 1: Construct an evaluation index system; based on the characteristics of the medium-temperature chilled water system, select core indicators to construct an evaluation index system; the core indicators include: energy efficiency ratio EER, cooling capacity, initial investment cost, operating energy consumption, carbon emission intensity;

[0006] Step 2: Determine the weight by the subjective and objective weighting method; among them, the subjective weighting uses the 1-9 scale method to construct a judgment matrix, screens the effective matrix through consistency test, and calculates the initial weight; the objective weighting corrects the initial weight according to the dispersion degree of expert scoring data;

[0007] Step 3: Calculate the grey relational degree of the system to be evaluated to quantify the comprehensive performance.

[0008] Preferably, in the step 1, the energy efficiency ratio EER includes: the energy efficiency ratio EERs of the central air conditioning system, the annual energy efficiency ratio EERsa of the central air conditioning system, the energy efficiency ratio EERr of the refrigeration machine room system, and the comprehensive energy efficiency ratio EERra of the refrigeration machine room system;

[0009] The air conditioning system evaluation indicators in the evaluation index system include: the coefficient of performance COP of the unit, the comprehensive coefficient of performance COPa of the unit, the integrated part-load performance coefficient IPLV of the unit, the chilled water transmission coefficient WTFchw, the cooling water transmission coefficient WTFcw, the energy efficiency ratio EERt of the air conditioning terminal, and the heat exchange efficiency of the cooling tower;

[0010] The initial investment cost includes: the purchase cost I1 of the air conditioning system equipment, the system installation and commissioning cost I2, and the material cost I3.

[0011] More preferably, the energy efficiency ratio EERs of the central air conditioning system is expressed as: Wherein, Q represents the refrigerating capacity, and ∑N i represents the annual power consumption of the air conditioning system equipment, and the air conditioning system equipment includes: chillers, cooling water pumps, cooling towers, and terminal equipment of the air conditioning system;

[0012] The energy efficiency ratio EERr of the refrigerating machine room system is:

[0013] The coefficient of performance COP of the unit is: Wherein, N chiller represents the energy consumption of the chiller;

[0014] The chilled water transmission coefficient WTFchw is: Wherein, N chp represents the energy consumption of the chilled water pump;

[0015] The cooling water transmission coefficient WTFcw is: Wherein, Q CW represents the heat transmitted by the cooling water, and N cp represents the energy consumption of the cooling water pump;

[0016] The energy efficiency ratio EERt of the air conditioning terminal is:

[0017] The heat exchange efficiency of the cooling tower is: Wherein, t in represents the inlet water temperature of the cooling tower, t out represents the outlet water temperature of the cooling tower, and t s represents the outdoor air wet bulb temperature.

[0018] Preferably, in the step 2, the consistency test formula for screening the effective matrix through the consistency test is:

[0019]

[0020] In formula (1), when CR ≤ 0.1, the matrix is effective, and λ max represents the maximum eigenvalue of the matrix, RI represents the random consistency index, and n represents the order of the judgment matrix.

[0021] More preferably, in the step 2, when objectively weighting and correcting the initial weight according to the discreteness of the expert scoring data, the weight corrected by the entropy method is:

[0022]

[0023] In formula (2), Hj is the entropy value of the j-th index, and wj is the initial weight of AHP.

[0024] Preferably, in step 3, the grey correlation degree formula for grey correlation degree calculation is:

[0025]

[0026] In formula (3), Δik represents the index difference, and ρ represents the discrimination coefficient (usually taken as 0.5). The beneficial effects of the present invention are:

[0027] 1. By combining subjective and objective weight assignment, the present invention reduces the subjective deviation of weight distribution. Therefore, the present invention can avoid the influence of subjective preference or data distribution on the weight in the comprehensive performance evaluation of the air conditioning system, and enhance the scientificity and universality of the evaluation results.

[0028] 2. By using grey correlation analysis, the present invention adapts to small sample and non-normal distribution data, and improves the universality of the evaluation system. Therefore, the comprehensive performance evaluation method of the air conditioning system of the present invention does not require a large number of samples or strict distribution assumptions, and is especially suitable for the comprehensive performance comparison of emerging technologies (such as medium-temperature chilled water systems).

[0029] 3. The present invention can horizontally compare the comprehensive performance of different schemes (such as medium-temperature chilled water systems and traditional systems) to guide energy-saving optimization. Therefore, the comprehensive performance evaluation method of the air conditioning system of the present invention can comprehensively reflect the energy efficiency, economic and environmental benefits of the system, and avoid the problem of single index in traditional evaluations. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic technical route diagram of a comprehensive performance evaluation method for a medium-temperature chilled water central air conditioning system of the present invention;

[0031] Figure 2 is a flowchart of the grey multi-level comprehensive evaluation method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] The following will clearly and completely describe the related technologies in the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] Reference Figures 1-2 provides a comprehensive evaluation method for a medium-temperature chilled water central air conditioning system combining subjective and objective weight assignment and grey correlation analysis, which solves the problems of large weight assignment deviation and poor adaptability to small sample data in the prior art, and improves the scientificity and practicability of the evaluation results.

[0034] 1. Construction of evaluation index system

[0035] Based on the characteristics of medium-temperature chilled water systems, select the energy efficiency ratio (EER), refrigerating capacity, initial investment cost, operating energy consumption, carbon emission intensity, etc. as the core indicators, as shown in Table 1:

[0036] Table 1

[0037]

[0038]

[0039]

[0040] 2. Determination of weights by subjective and objective weighting methods

[0041] Subjective weighting (Analytic Hierarchy Process):

[0042] Use the 1-9 scale method to construct a judgment matrix, screen the effective matrix through consistency test, and calculate the initial weights. The consistency test formula is:

[0043]

[0044] Among them, when CR ≤ 0.1, the matrix is effective, λ max is the maximum eigenvalue of the matrix, RI is the random consistency index, and n represents the order of the judgment matrix.

[0045] Objective weighting (Entropy method):

[0046] Modify the initial weights according to the dispersion degree of expert scoring data. The weight modified by the entropy method is:

[0047]

[0048] Among them, Hj is the entropy value of the j-th index, and wj is the AHP initial weight.

[0049] 3. Grey relational comprehensive evaluation:

[0050] Calculate the grey relational degree between the system to be evaluated (such as medium-temperature chilled water systems with different energy-saving schemes) and the ideal system to quantify the comprehensive performance. The grey relational degree formula is:

[0051]

[0052] Among them, Δik is the index difference, and ρ is the resolution coefficient (usually taken as 0.5).

[0053] The key technical points of this implementation method are:

[0054] 1. The weight allocation method combining subjective and objective weighting methods

[0055] Importance: Core innovation, solving the deviation problem of traditional single empowerment methods.

[0056] Analytic Hierarchy Process (AHP): Construct a judgment matrix based on the 1-9 scale method, and ensure the logical rationality of subjective empowerment through consistency check (CR ≤ 0.1).

[0057] Entropy method correction: Dynamically adjust the initial weight according to the dispersion degree (entropy value) of expert scoring data to improve objectivity.

[0058] Beneficial effects: Avoid the influence of subjective preferences or data distribution on weights, and enhance the scientificity and universality of evaluation results.

[0059] 2. Comprehensive evaluation method of grey relational analysis

[0060] Importance: Core innovation, solving the evaluation problem of small sample and non-normal distribution data.

[0061] Grey relational degree formula: Quantify the comprehensive performance by calculating the relational degree between the system to be evaluated and the ideal system (Formula 3).

[0062] Parameter setting: The resolution coefficient (ρ = 0.5) optimizes the sensitivity of the relational degree and adapts to the grey characteristics of the medium-temperature chilled water system.

[0063] Beneficial effects: Do not require a large number of samples or strict distribution assumptions, and are especially suitable for the comprehensive performance comparison of emerging technologies (such as medium-temperature chilled water systems).

[0064] 3. Construction of multi-dimensional evaluation index system

[0065] Importance: Supporting innovation, providing a structured basis for empowerment and evaluation.

[0066] Index classification: The first-level indicators cover energy efficiency performance (EER, part-load efficiency), economy (initial investment, maintenance cost), and environmental benefits (carbon emissions, noise).

[0067] Basis for index screening: Closely follow the characteristics of the medium-temperature chilled water system (such as the demand for energy efficiency optimization in the medium-temperature section) and the green building evaluation standard.

[0068] Beneficial effects: Comprehensively reflect the energy efficiency, economy and environmental benefits of the system, and avoid the problem of single index in traditional evaluation.

[0069] In summary, the present invention combines subjective and objective empowerment to reduce the subjective deviation of weight allocation. Therefore, the present invention can avoid the influence of subjective preferences or data distribution on weights in the comprehensive performance evaluation of air-conditioning systems, and enhance the scientificity and universality of evaluation results.

[0070] It should be emphasized that the above are only the preferred embodiments of the present invention, and there is no limitation to the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A comprehensive performance evaluation method for a medium-temperature cold water central air conditioning system, characterized in that: The following steps are involved: Step 1: Construct an evaluation index system; based on the characteristics of the medium-temperature cold water system, select core indicators to construct an evaluation index system; the core indicators include: energy efficiency ratio EER, cooling capacity, initial investment cost, operating energy consumption, and carbon emission intensity; Step 2: Determine the weights by subjective and objective weighting method; subjective weighting uses 1 to 9 scaling method to construct a judgment matrix, selects valid matrices through consistency test, and calculates initial weights; objective weighting modifies initial weights according to the discrete degree of expert scoring data; Step 3: Calculate the grey correlation of the system to be evaluated and quantify its comprehensive performance.

2. A comprehensive performance evaluation method for a medium-temperature cold water central air conditioning system according to claim 1, characterized in that: In the step 1, the energy efficiency ratio EER includes: the energy efficiency ratio EERs of the central air conditioning system, the annual energy efficiency ratio EERsa of the central air conditioning system, the energy efficiency ratio EERr of the refrigeration room system, and the comprehensive energy efficiency ratio EERra of the refrigeration room system; The air conditioning system evaluation indicators in the evaluation index system include: unit performance coefficient COP, unit comprehensive performance coefficient COPa, unit comprehensive part load performance coefficient IPLV, chilled water delivery coefficient WTFchw, cooling water delivery coefficient WTFcw, air conditioning terminal energy efficiency ratio EERt, cooling tower heat exchange efficiency; The initial investment cost includes: air conditioning system equipment purchase cost I1, system installation and commissioning cost I2, and material cost I3.

3. A comprehensive performance evaluation method for a medium-temperature cold water central air conditioning system according to claim 2, characterized in that: The energy efficiency ratio EERs of the central air conditioning system is expressed as: Where Q represents the cooling capacity, ∑N i Indicates the annual power consumption of air conditioning system equipment, which includes: chillers, cooling water pumps, cooling towers, and air conditioning system terminal equipment; The energy efficiency ratio EERr of the refrigeration room system is: The unit performance coefficient COP is: Among them, N chiller Indicates the energy consumption of the chiller; The chilled water transport coefficient WTFchw is: Among them, N chp Indicates the energy consumption of the chilled water pump; The cooling water transport coefficient WTFcw is: Among them, Q CW Indicates the heat transported by cooling water, N cp Indicates the energy consumption of cooling water pump; The air conditioning terminal energy efficiency ratio EERt is: The heat exchange efficiency of the cooling tower is: Among them, t in Indicates the cooling tower inlet water temperature, t out Indicates the cooling tower outlet water temperature, t s Indicates the outdoor air wet bulb temperature.

4. A comprehensive performance evaluation method for a medium-temperature cold water central air conditioning system according to claim 1, characterized in that: In step 2, the consistency check formula for screening the valid matrix through consistency check is: In formula (1), λ max represents the maximum eigenvalue of the matrix, RI represents the random consistency index, and n represents the order of the judgment matrix.

5. A comprehensive performance evaluation method for a medium-temperature cold water central air conditioning system according to claim 4, characterized in that: In step 2, when objective weighting modifies the initial weight according to the discrete degree of the expert scoring data, the entropy method modifies the weight as follows: In formula (2), Hj is the entropy value of the jth indicator, and wj is the initial weight of AHP.

6. A comprehensive performance evaluation method for a medium-temperature cold water central air conditioning system according to claim 1, characterized in that: In step 3, the grey relational degree formula for grey relational degree calculation is: In formula (3), Δik represents the index difference, and ρ represents the resolution coefficient.

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