C# 两个时间段中间时刻

/// <summary>
        /// 返回一个时间
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public DateTime returnTime()//返回随机时间
        {
            DateTime dt_now = DateTime.Now;
            DateTime dt_page = returnPageTime();//其他地方获取到的时间

            DateTime dateTimeMin = Convert.ToDateTime(dt_page);
            DateTime dateTimeMax = Convert.ToDateTime(dt_now);
            dateTimeMax = dateTimeMax.AddDays(3);

            TimeSpan ts = dateTimeMax - dateTimeMin;
            DateTime rTime = DateTime.Now;
            do
            {
                Random r = new Random();
                //int t1 = r.Next(0, (int)ts.TotalDays);
                int t2 = r.Next(0, (int)ts.TotalHours);
                //int t3 = r.Next(0, (int)ts.TotalMinutes);
                //int t4 = r.Next(0, (int)ts.TotalDays);

                DateTime newDT = dateTimeMin.Add(new TimeSpan(0, t2, 0, 0));

                Random random = new Random((int)(DateTime.Now.Ticks));

                int hour = random.Next(7, 22);
                int minute = random.Next(0, 60);
                int second = random.Next(0, 60);
                string tempStr = string.Format("{0} {1}:{2}:{3}", newDT.ToString("yyyy-MM-dd"), hour, minute, second);
                rTime = Convert.ToDateTime(tempStr);
            }
            while (rTime >= dateTimeMax || rTime <= dateTimeMin);


            return rTime;
        }