Principle and application of hybrid hot water system in residential solar energy hot water system
1 construction of a hybrid hot water system
In the hybrid hot water system, in order to reduce home energy expenditure is the basic principle of system design, therefore, the heat source unit heat and low cost in the operation process will be in the first place, as the basic system configuration of the heat source and heat source device using the device to obtain priority, only in the basic the heat source device can not meet the use requirements, the auxiliary heat source device was put into operation.
In general, the heat source device operating costs lower purchase costs, for example, operation cost of solar water heater is almost zero, and the operation cost of pump system is usually only about 1/3 of the electric heating device; heat source device to lower operating expenses as influenced by the environment, the solar energy water heater heating capacity is affected by sunlight conditions. Greater impact and heating capacity of air source heat pump under ambient temperature; the performance of heat source device of high operation cost is relatively stable, gas heating device and electric heating device belongs to this kind of products. Therefore, in a multi heat integrated product, gas heating and electric heating devices are usually used as auxiliary heat sources, while solar energy and heat pump units are usually used as the basic heat sources.
The typical configuration of the basic hybrid hot water system developed by Vanward is a solar thermal utilization device, air source heat pump unit and a gas heating device three heat source device integrated heat source system, usually the need for a heat storage tank, which is in several heat source device as thermal energy storage and heat transfer device connected to the supply side. Because the basic function of three kinds of heat source device is the same, and favorable operating conditions and time are different, so the problems existing in the optimal operation of the system, consumers can not achieve system optimization by artificial means, the system controller for various heat source device since the implementation of optimal operation management is essential for the main economy of the system operation with the effect.
The energy cascade utilization technology of hybrid solar hot water system, the cycle components will be solar thermal utilization device and heat pump unit and a gas heating device of three kinds of system combined by a system controller control system, can start the solar energy heat utilization device, heat pump or gas heating unit, or two units, three units start at the same time, the rational use of solar energy and environmental heat source and fuel gas to achieve energy saving, environmental protection, healthy and sustainable supply of hot water, used in a variety of living environment can get stable and hot water.
In order to obtain better technical economy, three for sanitary hot water heating system, solar collector capacity is usually according to the total load of the system from 1/4 to 1/2 configuration, air source heat pump capacity according to the total load of the system from 1/2 to 3/4 configuration, the gas heating unit capacity is usually according to the total load of the system configuration of 1/2 ~ 1. The total load of general system is the biggest load throughout the year, but in the actual operation conditions, all running time is usually more than 80% hours less than the 2/3 load, so the gas heating device running on only heat peak demand for a short time, as a backup source operation or other tropical fault source. If simplified as a dual heat source system, it is recommended that a solar heat collector be integrated with a gas heating device, or that an air source heat pump unit is integrated with a gas heating device.
If the solar collector and the air source heat pump device integration, in order to make the air source heat pump in critical ambient temperature still meet the heat load of 100%, air source heat pump to greatly increase the cost, because the running time of the year, the air source heat pump may have 80% hours less than the 2/3 load however, in order to obtain the heating capacity of the remaining 1/3, heat pump cost significantly exceed the original cost increase usually 1/3.
The system used for heating and sanitary hot water, heat pump for heating and hot water in the transition season (ambient temperature more than -7 DEG C) advantage is very outstanding, but need to pay attention to, the most favorable operation parameters by using heat pump heating is low temperature floor heating or similar radiation heating, therefore, the condensing temperature of the heat pump device for economic pump close operation. Figure 2 shows the relationship between operating conditions and performance coefficient (COP) of the heat pump. COP is defined as the heating capacity per unit electric consumption. It is the most important economic index of operation, and the higher COP value means that the heat pump is less power efficient. In addition, with the summer air-conditioning refrigeration function of heat pump in cooling operation, the use of waste heat heating hot water heat pump discharge, from this point of view, then the hot water is no need to pay the cost of energy. This product in the middle of the last century in Japan in 80s after the bulk of the market, has been the mainstream of heat pump water heater products, the current annual sales in the Japanese market is about 500 thousand units, the market share of about 50%. Obviously, affect the heating performance of gas heating boiler is almost not affected by meteorological conditions, and the water temperature can reach 80 DEG C, however, and if the air source heat pump integrated operation, should also be possible to run the operation state of low temperature water.
There are two kinds of solar collectors used in this kind of system, one is heating the sanitary hot water, the other is heating the two. Before an application for summer and cold winter cold area, system construction and operation management is relatively simple, winter solar collector heat supply is not enough to use the auxiliary heat source supplementary heating; summer off other heat source device, solar thermal device independent operation. The latter is the use of daylight.