Smart House Water Consumption Systems

Xiang Zheng Tu

 

Our smart house water consumption systems are based on proven thermal water flow sensors. As shown in the above figure, the smart house water consumption system mainly consists of a variable frequency water pump, a house water filter, two POSIFA’s thermal water flow sensors and a smart phone.

A thermal water flow sensor is made up of two thermopiles, which is used as the sensing temperature difference element and operated in conjunction with a resistive heater element for thermoelectric sensing. The water mass flow passing through the thermal sensor is calculated on the basis of the measured temperature difference between the hot and cold junctions of the thermopile, and the thermal conductivity coefficient, electric heat rate and specific heat of water. Compare with other type of water flow sensors the thermal water flow sensors have the advantages as:

·       Thermal water flow sensors have no moving part and no any mechanical failures to take place.

·       Thermal water flow sensors are MEMS devices with small size, higher sensitivity, higher reliability, low power consumption, ease of fabrication, and low cost.

·       Thermal water flow sensors calculate mass flow rather than volumetric flow and do not require temperature or pressure correction, which means there is no additional expense for the purchase and installation of additional equipment.

·       Thermal water flow sensors provide excellent accuracy and repeatability over a wide range of flow rates using bypass flow tube design. The sensor is placed in a bypass around a restriction in the main pipe and is sized to operate in the laminar flow region over its full operating range. 

·       Thermal conductivity water flow sensors are not influenced by the air bubbles entrained in the water. The effect of the bubbles can be added to the series conductivity by using conductivity of the air-water mixture for the water conductivity. The thermal conductivity of continuous water phase with entrapped air bubbles can be calculated.

The variable frequency water pump is equipped with a viable frequency drive. The viable frequency drove is used to adjust the speed of an electric motor by modulating the power being delivered. It provides continuous control, matching motor speed to the specific demands of the water flow. This makes the pump more efficient and also saves the user money by reducing excess energy from being wasted. When a user implements the variable frequency pump benefits are experienced over the life cycle of the pump. On an average 85 percent of a pump’s life cycle cost is attributed to its energy consumption and only 15 percent the actual cost of the pump motor. Motors associated with pumps tend to be sized where the pump may to meet peak loads, but not necessarily for normal continuous operation. Typically, for every 1 percent reduction in the variable frequency drive output the user can save 2.7 percent of energy costs. As energy consumptions continue to rise, it will become more imperative to find ways to cut energy consumption. Variable frequency water pump application is a key aspect to this effort.

The variable frequency drive is controlled to maintain a constant water flow in the output pipe. The down thermal water flow sensor measures the flow rate in the pipe to the water service and as this change sends a signal to the smart phone, which in turn sends a speed demand signal to the drive and this in turn adjust the speed of the motor so that the water flow rate reaches the presetting value. 

The water flow date measured by the down thermal flow sensor can be reviewed and analysis by the smart phone. The screen of the smart phone displays variety of water flow readings including average, minimum, maximum water flow rate, and total water and energy consumption in a month or year. With these data users may understand exactly when, where and how much water they’re consuming in their home on a daily basis.

The water filter takes away impurities from water, like chlorine taste, odor, zinc, copper, cadmium, and mercury. There are several water filters for soft water filtration like activated carbon filters, reverse osmosis, alkaline water ionizers, UV filters, and infrared filters. These filters are inexpensive but they require frequent replacements. Replacing water filter depends on several factors. Water filters typically have an estimated life cycle. However, this is only a guideline based on average water use. This isn't always a good indicator since water use varies per user. Referencing to the figure, the up thermal flow sensor and down thermal flow sensor respectively monitor the input and output water flow rate of the water filter. When the drop in flow rate passes a predetermined value then it’s time to change the filter.