//9 Tips to know what is the condenser temperature of water chillers

9 Tips to know what is the condenser temperature of water chillers

Here are 9 Tips to know what is the condenser temperature of water chillers.

 

1. What are the condenser pressure and condenser temperature of water chiller?

Condensation temperature is the saturation temperature of refrigerant steam in the condenser at a certain pressure. The condensation temperature is not equal to the temperature of the cooling medium, and there is a difference in heat transfer temperature between them.

Condensing pressure is the pressure at which the refrigerant condenses into a liquid in the condenser. Because the pressure inside the condenser in the cooling system can not be measured, in fact, the pressure drop of the refrigerant in the exhaust pipe and in the condenser is very small. No matter design debugging or maintenance, generally considered that the exhaust pressure is approximately equal to the condensation pressure.

 

2.The relationship between condenser temperature and condenser pressure

The lower the condenser pressure (high pressure), the lower the condenser temperature;

The higher the condenser pressure (high pressure), the higher the condenser temperature.

Let’s take a brief look at the curve of condenser pressure versus condenser temperature for R410:

 

From the graph can be seen very simple, condenser temperature and condenser pressure are proportional to change, condenser pressure and the temperature is corresponding.

3. Estimation of condenser temperature 

In refrigeration equipment debugging, we often need to know the condenser temperature of water chiller and calculate the condenser pressure (high pressure or exhaust pressure), so that can judge whether the water chiller system is a problem;

The most commonly used is to determine whether the water chiller lack of refrigerant.

Here is an empirical estimate for you :

Condensing temperature ambient temperature / water temperature + (10 ~ 20 °C) .

Example 1:

In summer, when the air-conditioned outdoor environment is around 35 degrees, we can estimate the temperature at this time the condensation temperature
35 + (10 ~ 20 °C)50 °C, according to the temperature and pressure table, it is easy to find that the evaporation pressure at this time is about 3.05 MPA (absolute pressure, R410A refrigerant) ;

Example 2:

Water Chillers, the Cooling Tower is known to book a temperature of 25 degrees, then how much is the condenser temperature of the water chiller?

Evaporation temperature 25 + (10 ~ 20)40 °C, according to the temperature and pressure table, it is easy to find that the condensation pressure at this time is about1.55 MPA (absolute pressure, R410 refrigerant)

With this condenser pressure, we can make a comparison with the water chiller system high-pressure table, can determine whether the water cooling system is normal, high pressure, in the end, is too high or too low, for maintenance debugging or very useful.

 

4.The relationship between condensing temperature and Power of Water Chiller

Let’s start with an animation:

 

From the t-s image, it is obvious that if the condensing temperature of the water chiller system is increased, the power consumed is increased;

The reason is very simple, condenser temperature increased, in the evaporation temperature constant, the compressor pressure ratio increased, and the power of the compressor is proportional to the pressure ratio, that is, the pressure ratio increased, the power of the compressor also increased.

It can be understood as follows:

The compressor compresses 5 kg of refrigerant to 15 kg of power; certainly more power than the compressor compresses 5 kg of refrigerant to 25 kg.

 

5.The relationship between condensing temperature and refrigerating capacity

The same animation above:

 

 

From the t-s image in the animation, it is easy to see that the condensing temperature increases, the cooling capacity of the system will be reduced.

Here to explain the reason, due to the increase in condensing temperature, resulting in the refrigerants per unit cooling capacity will be reduced, in the same refrigerant mass flow, the system of cooling capacity will be reduced.

6.The relationship between heat load and evaporation pressure

The short answer is the condensing side of the load and condensing pressure relationship.
Under a constant operating condition (refrigerant flow), the higher the heat load, the higher the condensation pressure, and vice versa. We can imagine that when you design the condenser small (thermal load is relatively large), the refrigeration system is very easy to alarm the high pressure.

7.Analysis of abnormal evaporation temperature during overhaul

1. Low condenser temperature

There are many reasons for the low evaporation temperature. The reason is that there is less refrigerant in the evaporator or the throttle valve has a bad throttling effect

1. Expansion Valve selection is large;
2. Expansion Valve failure or expansion valve opening too large, there is no throttling effect;
3. The refrigerant charge of the cooling system is not enough;
4. The refrigeration system lacks refrigerant

1 ~ 2 main analysis of expansion valve throttling effect, 3 ~ 4 main analysis of the lack of refrigerant;

2. High condensation temperature

(1) the low flow rate of cooling water (or Air), high temperature;

(2) There is air in the system, which makes the condensation pressure rise;

(3) Refrigerant charge is excessive, liquid occupied effective condensation area;

(4) The condenser disrepair, heat transfer surface fouling serious, can also lead to high condensation pressure. The existence of scale has a great influence on the condensation pressure.

There are many other reasons:

1. There is more refrigerant in the condenser
2. Cooling Systems have other magazines that occupy the condenser heat transfer area.
3. The condenser does not condense well

8. How to solve if high condenser pressure happen?

When the condensation pressure rises, the compressor exhaust temperature also rises.

The compressor compression ratio increases, the gas transmission coefficient decreases, so that the compressor refrigeration capacity decreases. Increased power consumption.
If the exhaust temperature is too high, it will increase the consumption of compressor lubricating oil, make the oil thinner and affect lubrication; when the exhaust temperature is close to the compressor oil flash point, it will also cause part of the lubricating oil to carbonize and accumulate at the suction and discharge Valve Ports Affect the sealing ability of valve.

There are two ways to be considered:

1. Lowering the temperature of cooling medium can reduce the condensation temperature and the condensation pressure, but it is difficult to choose because of the limitation of the environment.

2. Increasing the flow rate of cooling medium can reduce the condensation temperature a little. But cannot one-sided increase the cooling water or air flow, because this will increase the cooling water pump or fan and motor power, should be a comprehensive consideration.

The higher exhaust pressure will increase the compression work and decrease the gas transmission coefficient, which will decrease the cooling efficiency.

9. How to control the condenser temperature of water chiller?

Today, we will talk about the condensation experiment in the heat exchanger experiment. Compared with the evaporator experiment, the condenser experiment is relatively simple. There are three controlled parameters, as follows:

A: Condenser inlet pressure

B: Condenser inlet temperature

C: Condenser outlet temperature

Condenser outlet pressure is not required to control;

Why control these three variables, it is very simple, the principle is the same as the evaporation experiment.

How is the condense temperature controlled?

In fact, control the condenser inlet pressure, you can control the condensing pressure condenser, because the pressure drop condenser is actually very small, approximately as the inlet pressure is equal to the condensing pressure. So how to control the import pressure?

There are several ways to do this:

1. Control the air volume of the flow-through condenser. If the air volume is large, the condensing pressure will naturally drop

2. The inlet pressure of the condenser is controlled by the water flow rate or temperature.

 

 

 

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By |2018-11-29T17:49:28+00:00November 15th, 2018|Updates|