Abstract
A microcontroller based, thermal energy meter cum controller (TEMC) suitable for solar thermal systems has been developed. It monitors solar radiation, ambient temperature, fluid flow rate, and temperature of fluid at various locations of the system and computes the energy transfer rate. It also controls the operation of the fluid-circulating pump depending on the temperature difference across the solar collector field. The accuracy of energy measurement is ±1.5%. The instrument has been tested in a solar water heating system. Its operation became automatic with savings in electrical energy consumption of pump by 30% on cloudy days.

1 Introduction
Solar water heating systems find wide applications in industry to conserve fossil fuel like oil, coal etc. They employ motor driven pumps for circulating water with on-off controllers and calls for automatic operation. Reliability and performance of the system depend on the instrumentation and controls employed. Multi-channel temperature recorders, flow meters, thermal energy meters are the essential instruments for monitoring and eva luating the performance of these systems. A differential temperature controller (DTC) is required in a solar water heating system for an automatic and efficient operation of the system. To meet all these requirements, a microcontroller based instrument was developed. Shoji Kusui and Tetsuo Nagai [1] developed an electronic heat meter for measuring thermal energy using thermistors as temperature sensors and turbine flow meter as flow sensor.

摘 要
適用于太陽(yáng)能熱系統(tǒng)的單片機(jī)熱能表控制器（TEMC）已經(jīng)研制成功。它能夠監(jiān)測(cè)太陽(yáng)輻射，空氣溫度，流體速度，在不同地點(diǎn)系統(tǒng)的流體溫度和計(jì)算能量的傳輸速率。它也能根據(jù)全國(guó)太陽(yáng)能極熱地的溫差來(lái)控制流體循環(huán)泵的操作。電能計(jì)量準(zhǔn)確度為± 1.5％。該儀器已經(jīng)過(guò)太陽(yáng)能供熱水系統(tǒng)的測(cè)試。陰天自動(dòng)調(diào)到節(jié)能模式節(jié)能70％。

1 緒 論
太陽(yáng)能熱水系統(tǒng)在工業(yè)上有著廣泛的應(yīng)用，因?yàn)樗芄?jié)約化石燃料如石油，煤炭等。使用電機(jī)驅(qū)動(dòng)泵和開(kāi)關(guān)控制器自動(dòng)循環(huán)水源。系統(tǒng)的性能和可靠性依賴(lài)于儀器的精度和控制。多通道溫度記錄儀，流量計(jì)，熱能表，負(fù)責(zé)監(jiān)察和評(píng)估這些系統(tǒng)性能的重要手段。溫差控制器（DTC）是一種能夠自動(dòng)高效的運(yùn)作太陽(yáng)能熱水系統(tǒng)的控制器。為了滿(mǎn)足所有這些要求，基于微控制器的儀器已經(jīng)開(kāi)發(fā)。Shoji Kusui和Tetsuo Nagai發(fā)明了一種電子熱能表，用于測(cè)量熱能。這種表使用了熱敏電阻和作為流量傳感器的渦輪流量計(jì)。