Study on plate heat exchanger and heating
The heat transfer coefficient exceeds 3 times of the heat transfer coefficient of the tube type water heater, and the experimental results show that the performance of the plate type water heater is much higher than that of the traditional water heater. Analysis of the reasons, mainly because the pipe type water heater tube outer space, the velocity is very small, the heat transfer coefficient is very low, and in the 10mm copper tube flow rate is too large, the distance is about 20m, so the tube resistance is too large, the result is the consumption of a lot of data, but the efficiency is still very low. Plate type water heater in both sides of the fluid velocity is more appropriate, although the flow is tortuous channel, but because of the short flow distance, and therefore in the high heat transfer coefficient, while the flow resistance is not large. Plate type water heater data consumption is less, even if the price and radical water heater type flat, also can ensure a reasonable profit.
With less equipment cost, use can be used in the existing heating system and tap water system heat type water heater heating water heating tap water resources. The cost of energy supply living hot water less, so it has been gradually recognized by the market and users. Assuming the average daily ordinary families required quantity of water is 100L, if the heating to 30 Deg. C, the required heat is 12600kJ, if the use of gas heating, gas consumption costs about 1.7 yuan /d; if you use the electric heating costs about 2.02 yuan /d; and if the heating water for heating, it costs about 0.63 yuan /d. And does not significantly affect the heating quality.
Currently on the market of water heater is mainly used for manufacturing the copper tube and cast iron shell, its huge size and quality about 50kg, although recently useful water heater stainless steel casing tube come out, make a single water heater to reduce the quality of 810kg, but the volume is still relatively large, and the cost increase. The heating water heater has a higher heat transfer coefficient in the inner side of the pipe, which is characterized by high flow rate and turning, and the cross section of the shell side channel is large, the flow rate is low, the heat transfer coefficient is very low, and the overall heat transfer coefficient is low. When the water supply temperature is below 70 DEG C, it can not meet the heating requirements. In addition, if the water pressure is low, it is difficult to overcome the flow resistance in the slender copper pipe, and the hot water is very small. Can be seen on the market at present, the use of heating water heater technology content is low, poor performance.
Hot and cold fluid flow through the 4 guide plates at both ends of the through hole and the structure and characteristics of brazing type heat exchanger brazing type water heater is a heat exchanger composed of stainless steel corrugated plate. And the flow and heat transfer in the interphase channel. The plate type water heater has the advantages of high heat transfer efficiency, compact structure, reliable quality and low interest rate. The author and the relevant units of the plate type water heater (Figure 1 in the use of corrugated plate enhanced heat transfer technology, so that both sides of the fluid flow in the tortuous channel countercurrent heat transfer, can exponentially increase the heat transfer coefficient. The shape is much more than the existing copper shell body product is compact, and the performance has reached the brazing plate type heat exchanger abroad level, but the price is very low.
From the point of view of safety performance, the pressure level of the brazing plate type water heater reaches 3MPa, far beyond the requirements of HVAC equipment. Because the water heater by the heat source temperature and pressure limits, may not occur above the heating water or tap water pressure in operation, so it is absolutely safe due to the washing fluid by turning in the twists and turns when the channel, the corrugated channel scaling faster than the scaling speed straight channel is much slower, and can there is no need to worry about the problem of automatic shedding, scaling and channel blockage. However, if there is a fibrous substance in the water system, the filter should be considered. If the use of many years after the heat transfer effect is found to be able to take into account the use of the water heater to turn around and exchange channels to use the method of reverse wash away dirt.
Pipe type water heater the size of 200mm800mm, comparing the experimental results with stainless steel tube to tube plate type water heater has been developed and purchased from the market on the 1 copper water heater (hereinafter referred to as the pipe type water heater) were compared to experimental performance. The plate type water heater size 312mm112mm32mm * width * thickness). The quality of both were 1.8kg and 8.6kg the 2 water heaters simultaneously in parallel experiments, the heating water volume flow through both to keep 6L/min, heating water inlet temperature is 5085 DEG, 5 DEG C each measuring a set of data. The inlet temperature of the tap water is 6 DEG C, and the volume flow rate is adjusted to 4.2L/min. The experimental results are shown in figure. The G represents the tube type water heater on the B. It can be seen that the water inlet temperature of heating tap water at the same temperature at the entrance of the plate type water heater than pipe type water heater is about 818 DEG C. If the required volume flow of hot water is 4.2L/min, the temperature is 40 DEG C, the heating water inlet temperature of the plate type water heater and the tube type water heater is respectively at the temperature of 53 DEG C and the temperature of 72 DEG C.
